Timing advance (ta) handling for sidelink (sl)-assisted positioning

ABSTRACT

Timing advance (TA) handling for sidelink (SL)-assisted positioning of a first user equipment (UE), comprises determining the first UE is configured to transmit an SL positioning reference signal (SL-PRS) to a second UE for the SL-assisted positioning. A guard period length can be determined based on a configuration of the first UE for transmitting the SL-PRS, where the guard period may comprise a period of time during which the SL-PRS is transmitted by the first UE. A message can be sent to a serving transmission reception point (TRP) of the first UE, where the message indicates the guard period and comprises a TA-related request. The TA-related request includes a request to postpone applying a TA command received by the first UE until after the guard period, or a request for the serving TRP not to send a TA command to the first UE during the guard period

RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional applicationSer. No. 17/160,593, filed Jan. 28, 2021, entitled “TIMING ADVANCE (TA)HANDLING FOR SIDELINK (SL)-ASSISTED POSITIONING,” which is assigned tothe assignee hereof and incorporated by reference herein in itsentirety.

BACKGROUND 1. Field of Invention

The present invention relates generally to the field of wirelesscommunications, and more specifically to determining the location of aUser Equipment (UE) using radio frequency (RF) signals.

2. Description of Related Art

The use of a sidelink (SL) interface in the positioning of a UE forwhich a position is to be determined (or “target UE”) may be similar inways to the use of base stations. However, unlike base stations, UEsused to position the target UE (or “anchor UEs”) may be subject toTiming Advance (TA) commands. These commands can impact the transmissiontimes of reference signals used to position the target UE, which, inturn, can impact the accuracy of the position estimate of the target UE.Applicable communication standards for SL-based positioning currentlyhave no way of accounting for these TA commands.

BRIEF SUMMARY

An example method of timing advance (TA) handling for sidelink(SL)-assisted positioning of a first user equipment (UE), according tothis disclosure, comprises determining the first UE is configured totransmit an SL positioning reference signal (SL-PRS) to a second UE toperform the SL-assisted positioning. The method also comprisesdetermining a length of time for a guard period based on a configurationof the first UE for transmitting the SL-PRS, where the guard period maycomprise a period of time during which the SL-PRS is transmitted by thefirst UE. The method also comprises sending, to a serving transmissionreception point (TRP) of the first UE, a message indicating the guardperiod and may comprise a TA-related request, where the TA-relatedrequest includes: a request to postpone applying a TA command receivedby the first UE until after the guard period, or a request for theserving TRP not to send a TA command to the first UE during the guardperiod.

Another example a method of timing advance (TA) handling for sidelink(SL)-assisted positioning of a first user equipment (UE), according tothis disclosure, comprises receiving, at a serving transmissionreception point (TRP) of the first UE, a message from a network node,the message indicating a guard period and may comprise a TA-relatedrequest, where: the guard period may comprise a period of time duringwhich an SL positioning reference signal (SL-PRS) is transmitted by thefirst UE to a second UE; and the TA-related request may comprise: arequest to postpone applying a TA command received by the first UE untilafter the guard period, or a request for the serving TRP not to send aTA command to the first UE during the guard period. The method alsocomprises determining a response to the message based on an applicableTA priority condition. The method also comprises sending the response tothe network node.

An example device for providing timing advance (TA) handling forsidelink (SL)-assisted positioning of a first user equipment (UE),according to this disclosure, comprises a communication interface, amemory, and one or more processing units communicatively coupled withthe communication interface and the memory. The one or more processingunits configured to determine the first UE is configured to transmit anSL positioning reference signal (SL-PRS) to a second UE to perform theSL-assisted positioning. The one or more processing units are alsoconfigured to determine a length of time for a guard period based on aconfiguration of the first UE for transmitting the SL-PRS, where theguard period may comprise a period of time during which the SL-PRS istransmitted by the first UE. The one or more processing units are alsoconfigured to send, to a serving transmission reception point (TRP) ofthe first UE via the communication interface, a message indicating theguard period and may comprise a TA-related request, where the TA-relatedrequest includes: a request to postpone applying a TA command receivedby the first UE until after the guard period, or a request for theserving TRP not to send a TA command to the first UE during the guardperiod.

Another example device for providing timing advance (TA) handling forsidelink (SL)-assisted positioning of a first user equipment (UE),according to this disclosure, comprises a communication interface, amemory, and one or more processing units communicatively coupled withthe communication interface and the memory. The one or more processingunits are configured to receive, via the communication interface, amessage from a network node, the message indicating a guard period andmay comprise a TA-related request, where the guard period may comprise aperiod of time during which an SL positioning reference signal (SL-PRS)is transmitted by the first UE to a second UE; and the TA-relatedrequest may comprise a request to postpone applying a TA commandreceived by the first UE until after the guard period, or a request fora serving transmission reception point (TRP) not to send a TA command tothe first UE during the guard period. The one or more processing unitsare also configured to determine a response to the message based on anapplicable TA priority condition, and send, via the communicationinterface, the response to the network node.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a positioning system, according to an embodiment.

FIG. 2 is a diagram of a 5th Generation (5G) New Radio (NR) positioningsystem, illustrating an embodiment of a positioning system (e.g., thepositioning system of FIG. 1) implemented within a 5G NR communicationsystem.

FIGS. 3 and 4 are illustrations of different types of positioningmethods used to determine the location of a UE, according to anembodiment.

FIG. 5 is a simplified diagram illustrating how an anchor UE can be usedin the positioning of a UE in a 5G NR network, according to anembodiment.

FIG. 6 is a timing diagram illustrating an round trip signal propagationdelay (RTT) exchange 600 between two UEs, according to an embodiment.

FIG. 7 is a timing diagram illustrating a Time Difference Of Arrival(TDOA)-based measurement between two UEs, according to an embodiment.

FIGS. 8 and 9 are flow diagrams of methods of Timing Advance (TA)handling for sidelink (SL)-assisted positioning of a first UE, accordingto some embodiments.

FIG. 10 is a block diagram of an embodiment of a UE, which can beutilized in embodiments as described herein.

FIG. 11 is a block diagram of an embodiment of a base station, which canbe utilized in embodiments as described herein.

FIG. 12 is a block diagram of an embodiment of a computer system, whichcan be utilized in embodiments as described herein.

Like reference symbols in the various drawings indicate like elements,in accordance with certain example implementations. In addition,multiple instances of an element may be indicated by following a firstnumber for the element with a letter or a hyphen and a second number.For example, multiple instances of an element 110 may be indicated as110-1, 110-2, 110-3 etc. or as 110 a, 110 b, 110 c, etc. When referringto such an element using only the first number, any instance of theelement is to be understood (e.g., element 110 in the previous examplewould refer to elements 110-1, 110-2, and 110-3 or to elements 110 a,110 b, and 110 c).

DETAILED DESCRIPTION

The following description is directed to certain implementations for thepurposes of describing the innovative aspects of this disclosure.However, a person having ordinary skill in the art will readilyrecognize that the teachings herein can be applied in a multitude ofdifferent ways. The described implementations may be implemented in anydevice, system, or network that is capable of transmitting and receivingradio frequency (RF) signals according to any communication standard,such as any of the Institute of Electrical and Electronics Engineers(IEEE) IEEE 802.11 standards (including those identified as Wi-Fi®technologies), the Bluetooth® standard, code division multiple access(CDMA), frequency division multiple access (FDMA), time divisionmultiple access (TDMA), Global System for Mobile communications (GSM),GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment(EDGE), Terrestrial Trunked Radio (TETRA), Wideband-CDMA (W-CDMA),Evolution Data Optimized (EV-DO), 1×EV-DO, EV-DO Rev A, EV-DO Rev B,High Rate Packet Data (HRPD), High Speed Packet Access (HSPA), HighSpeed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access(HSUPA), Evolved High Speed Packet Access (HSPA+), Long Term Evolution(LTE), Advanced Mobile Phone System (AMPS), or other known signals thatare used to communicate within a wireless, cellular or internet ofthings (IoT) network, such as a system utilizing 3G, 4G, 5G, 6G, orfurther implementations thereof, technology.

As used herein, an “RF signal” comprises an electromagnetic wave thattransports information through the space between a transmitter (ortransmitting device) and a receiver (or receiving device). As usedherein, a transmitter may transmit a single “RF signal” or multiple “RFsignals” to a receiver. However, the receiver may receive multiple “RFsignals” corresponding to each transmitted RF signal due to thepropagation characteristics of RF signals through multipath channels.The same transmitted RF signal on different paths between thetransmitter and receiver may be referred to as a “multipath” RF signal.

FIG. 1 is a simplified illustration of a positioning system 100 in whicha UE 105, location server 160, and/or other components of thepositioning system 100 can use the techniques provided herein forhandling Timing Advance (TA) commands when determining an estimatedlocation of UE 105 using sidelink (SL)-assisted positioning, accordingto an embodiment. Again, when determining the position of a UE (e.g., UE105) it may be referred to as a “target UE.” The techniques describedherein may be implemented by one or more components of the positioningsystem 100. The positioning system 100 can include: a UE 105; one ormore satellites 110 (also referred to as space vehicles (SVs)) for aGlobal Navigation Satellite System (GNSS) such as the Global PositioningSystem (GPS), GLONASS, Galileo or Beidou; base stations 120; accesspoints (APs) 130; location server 160; network 170; and external client180. Generally put, the positioning system 100 can estimate a locationof the UE 105 based on RF signals received by and/or sent from the UE105 and known locations of other components (e.g., GNSS satellites 110,base stations 120, APs 130) transmitting and/or receiving the RFsignals. Additional details regarding particular location estimationtechniques are discussed in more detail with regard to FIG. 2.

It should be noted that FIG. 1 provides only a generalized illustrationof various components, any or all of which may be utilized asappropriate, and each of which may be duplicated as necessary.Specifically, although only one UE 105 is illustrated, it will beunderstood that many UEs (e.g., hundreds, thousands, millions, etc.) mayutilize the positioning system 100. Similarly, the positioning system100 may include a larger or smaller number of base stations 120 and/orAPs 130 than illustrated in FIG. 1. The illustrated connections thatconnect the various components in the positioning system 100 comprisedata and signaling connections which may include additional(intermediary) components, direct or indirect physical and/or wirelessconnections, and/or additional networks. Furthermore, components may berearranged, combined, separated, substituted, and/or omitted, dependingon desired functionality. In some embodiments, for example, the externalclient 180 may be directly connected to location server 160. A person ofordinary skill in the art will recognize many modifications to thecomponents illustrated.

Depending on desired functionality, the network 170 may comprise any ofa variety of wireless and/or wireline networks. The network 170 can, forexample, comprise any combination of public and/or private networks,local and/or wide-area networks, and the like. Furthermore, the network170 may utilize one or more wired and/or wireless communicationtechnologies. In some embodiments, the network 170 may comprise acellular or other mobile network, a wireless local area network (WLAN),a wireless wide-area network (WWAN), and/or the Internet, for example.Examples of network 170 include a Long-Term Evolution (LTE) wirelessnetwork, a Fifth Generation (5G) wireless network (also referred to asNew Radio (NR) wireless network or 5G NR wireless network), a Wi-FiWLAN, and the Internet. LTE, 5G and NR are wireless technologiesdefined, or being defined, by the 3rd Generation Partnership Project(3GPP). Network 170 may also include more than one network and/or morethan one type of network.

The base stations 120 and access points (APs) 130 are communicativelycoupled to the network 170. In some embodiments, the base station 120 smay be owned, maintained, and/or operated by a cellular networkprovider, and may employ any of a variety of wireless technologies, asdescribed herein below. Depending on the technology of the network 170,a base station 120 may comprise a node B, an Evolved Node B (eNodeB oreNB), a base transceiver station (BTS), a radio base station (RBS), anNR NodeB (gNB), a Next Generation eNB (ng-eNB), or the like. A basestation 120 that is a gNB or ng-eNB may be part of a Next GenerationRadio Access Network (NG-RAN) which may connect to a 5G Core Network(5GC) in the case that Network 170 is a 5G network. An AP 130 maycomprise a Wi-Fi AP or a Bluetooth® AP, for example. Thus, UE 105 cansend and receive information with network-connected devices, such aslocation server 160, by accessing the network 170 via a base station 120using a first communication link 133. Additionally or alternatively,because APs 130 also may be communicatively coupled with the network170, UE 105 may communicate with network-connected andInternet-connected devices, including location server 160, using asecond communication link 135.

As used herein, the term “base station” may generically refer to asingle physical transmission point, or multiple co-located physicaltransmission points, which may be located at a base station 120. ATransmission Reception Point (TRP) (also known as transmit/receivepoint) corresponds to this type of transmission point, and the term“TRP” may be used interchangeably herein with the terms “gNB,” “ng-eNB,”and “base station.” In some cases, a base station 120 may comprisemultiple TRPs—e.g. with each TRP associated with a different antenna ora different antenna array for the base station 120. Physicaltransmission points may comprise an array of antennas of a base station120 (e.g., as in a Multiple Input-Multiple Output (MIMO) system and/orwhere the base station employs beamforming). The term “base station” mayadditionally refer to multiple non-co-located physical transmissionpoints, the physical transmission points may be a Distributed AntennaSystem (DAS) (a network of spatially separated antennas connected to acommon source via a transport medium) or a Remote Radio Head (RRH) (aremote base station connected to a serving base station).

As used herein, the term “cell” may generically refer to a logicalcommunication entity used for communication with a base station 120 andmay be associated with an identifier for distinguishing neighboringcells (e.g., a Physical Cell Identifier (PCID), a Virtual CellIdentifier (VCID)) operating via the same or a different carrier. Insome examples, a carrier may support multiple cells, and different cellsmay be configured according to different protocol types (e.g.,Machine-Type Communication (MTC), Narrowband Internet-of-Things(NB-IoT), Enhanced Mobile Broadband (eMBB), or others) that may provideaccess for different types of devices. In some cases, the term “cell”may refer to a portion of a geographic coverage area (e.g., a sector)over which the logical entity operates.

The location server 160 may comprise a server and/or other computingdevice configured to determine an estimated location of UE 105 and/orprovide data (e.g., “assistance data”) to UE 105 to facilitate locationmeasurement and/or location determination by UE 105. According to someembodiments, location server 160 may comprise a Home Secure User PlaneLocation (SUPL) Location Platform (H-SLP), which may support the SUPLuser plane (UP) location solution defined by the Open Mobile Alliance(OMA) and may support location services for UE 105 based on subscriptioninformation for UE 105 stored in location server 160. In someembodiments, the location server 160 may comprise, a Discovered SLP(D-SLP) or an Emergency SLP (E-SLP). The location server 160 may alsocomprise an Enhanced Serving Mobile Location Center (E-SMLC) thatsupports location of UE 105 using a control plane (CP) location solutionfor LTE radio access by UE 105. The location server 160 may furthercomprise a Location Management Function (LMF) that supports location ofUE 105 using a control plane (CP) location solution for NR or LTE radioaccess by UE 105.

In a CP location solution, signaling to control and manage the locationof UE 105 may be exchanged between elements of network 170 and with UE105 using existing network interfaces and protocols and as signalingfrom the perspective of network 170. In a UP location solution,signaling to control and manage the location of UE 105 may be exchangedbetween location server 160 and UE 105 as data (e.g. data transportedusing the Internet Protocol (IP) and/or Transmission Control Protocol(TCP)) from the perspective of network 170.

As previously noted, and as discussed in more detail below, theestimated location of UE 105 may be based on measurements of RF signalssent from and/or received by the UE 105. In particular, thesemeasurements can provide information regarding the relative distanceand/or angle of the UE 105 from one or more components in thepositioning system 100 (e.g., GNSS satellites 110, APs 130, basestations 120). The estimated location of the UE 105 can be estimatedgeometrically (e.g., using multiangulation and/or multilateration),based on the distance and/or angle measurements, along with knownposition of the one or more components.

Although terrestrial components such as APs 130 and base stations 120may be fixed, embodiments are not so limited. Mobile components may beused. Moreover, in some embodiments, a location of the UE 105 may beestimated at least in part based on measurements of RF signalscommunicated between the UE 105 and one or more other UEs (not shown inFIG. 1), which may be mobile. Direct communication between the one ormore other UEs and UE 105 may comprise sidelink and/or similarDevice-to-Device (D2D) communication technologies. Sidelink, which isdefined by 3GPP, is a form of D2D communication under the cellular-basedLTE and NR standards.

An estimated location of UE 105 can be used in a variety ofapplications—e.g. to assist direction finding or navigation for a userof UE 105 or to assist another user (e.g. associated with externalclient 180) to locate UE 105. A “location” is also referred to herein asa “location estimate”, “estimated location”, “location”, “position”,“position estimate”, “position fix”, “estimated position”, “locationfix” or “fix”. A location of UE 105 may comprise an absolute location ofUE 105 (e.g. a latitude and longitude and possibly altitude) or arelative location of UE 105 (e.g. a location expressed as distancesnorth or south, east or west and possibly above or below some otherknown fixed location or some other location such as a location for UE105 at some known previous time). A location may be specified as ageodetic location comprising coordinates which may be absolute (e.g.latitude, longitude and optionally altitude), relative (e.g. relative tosome known absolute location) or local (e.g. X, Y and optionally Zcoordinates according to a coordinate system defined relative to a localarea such a factory, warehouse, college campus, shopping mall, sportsstadium or convention center). A location may instead be a civiclocation and may then comprise one or more of a street address (e.g.including names or labels for a country, state, county, city, roadand/or street, and/or a road or street number), and/or a label or namefor a place, building, portion of a building, floor of a building,and/or room inside a building etc. A location may further include anuncertainty or error indication, such as a horizontal and possiblyvertical distance by which the location is expected to be in error or anindication of an area or volume (e.g. a circle or ellipse) within whichUE 105 is expected to be located with some level of confidence (e.g. 95%confidence).

The external client 180 may be a web server or remote application thatmay have some association with UE 105 (e.g. may be accessed by a user ofUE 105) or may be a server, application, or computer system providing alocation service to some other user or users which may include obtainingand providing the location of UE 105 (e.g. to enable a service such asfriend or relative finder, asset tracking or child or pet location).Additionally or alternatively, the external client 180 may obtain andprovide the location of UE 105 to an emergency services provider,government agency, etc.

As previously noted, the example positioning system 100 can beimplemented using a wireless communication network, such as an LTE-basedor 5G NR-based network. FIG. 2 shows a diagram of a 5G NR positioningsystem 200, illustrating an embodiment of a positioning system (e.g.,positioning system 100) implementing 5G NR. The 5G NR positioning system200 may be configured to determine the location of a UE 105 by usingaccess nodes 210, 214, 216 (which may correspond with base stations 120and access points 130 of FIG. 1) and (optionally) an LMF 220 (which maycorrespond with location server 160) to implement one or morepositioning methods. Here, the 5G NR positioning system 200 comprises aUE 105, and components of a 5G NR network comprising a Next Generation(NG) Radio Access Network (RAN) (NG-RAN) 235 and a 5G Core Network (5GCN) 240. A 5G network may also be referred to as an NR network; NG-RAN235 may be referred to as a 5G RAN or as an NR RAN; and 5G CN 240 may bereferred to as an NG Core network. The 5G NR positioning system 200 mayfurther utilize information from GNSS satellites 110 from a GNSS systemlike Global Positioning System (GPS) or similar system (e.g. GLONASS,Galileo, Beidou, Indian Regional Navigational Satellite System (IRNSS)).Additional components of the 5G NR positioning system 200 are describedbelow. The 5G NR positioning system 200 may include additional oralternative components.

It should be noted that FIG. 2 provides only a generalized illustrationof various components, any or all of which may be utilized asappropriate, and each of which may be duplicated or omitted asnecessary. Specifically, although only one UE 105 is illustrated, itwill be understood that many UEs (e.g., hundreds, thousands, millions,etc.) may utilize the 5G NR positioning system 200. Similarly, the 5G NRpositioning system 200 may include a larger (or smaller) number of GNSSsatellites 110, gNBs 210, ng-eNBs 214, Wireless Local Area Networks(WLANs) 216, Access and mobility Management Functions (AMF)s 215,external clients 230, and/or other components. The illustratedconnections that connect the various components in the 5G NR positioningsystem 200 include data and signaling connections which may includeadditional (intermediary) components, direct or indirect physical and/orwireless connections, and/or additional networks. Furthermore,components may be rearranged, combined, separated, substituted, and/oromitted, depending on desired functionality.

The UE 105 may comprise and/or be referred to as a device, a mobiledevice, a wireless device, a mobile terminal, a terminal, a mobilestation (MS), a Secure User Plane Location (SUPL)-Enabled Terminal(SET), or by some other name. Moreover, UE 105 may correspond to acellphone, smartphone, laptop, tablet, personal data assistant (PDA),tracking device, navigation device, Internet of Things (IoT) device, orsome other portable or moveable device. Typically, though notnecessarily, the UE 105 may support wireless communication using one ormore Radio Access Technologies (RATs) such as using GSM, CDMA, W-CDMA,LTE, High Rate Packet Data (HRPD), IEEE 802.11 Wi-Fi®, Bluetooth,Worldwide Interoperability for Microwave Access (WiMAX™), 5G NR (e.g.,using the NG-RAN 235 and 5G CN 240), etc. The UE 105 may also supportwireless communication using a WLAN 216 which (like the one or moreRATs, and as previously noted with respect to FIG. 1) may connect toother networks, such as the Internet. The use of one or more of theseRATs may allow the UE 105 to communicate with an external client 230(e.g., via elements of 5G CN 240 not shown in FIG. 2, or possibly via aGateway Mobile Location Center (GMLC) 225) and/or allow the externalclient 230 to receive location information regarding the UE 105 (e.g.,via the GMLC 225). The external client 230 of FIG. 2 may correspond toexternal client 180 of FIG. 1, as implemented in or communicativelycoupled with a 5G NR network.

The UE 105 may include a single entity or may include multiple entities,such as in a personal area network where a user may employ audio, videoand/or data I/O devices, and/or body sensors and a separate wireline orwireless modem. An estimate of a location of the UE 105 may be referredto as a location, location estimate, location fix, fix, position,position estimate, or position fix, and may be geodetic, thus providinglocation coordinates for the UE 105 (e.g., latitude and longitude),which may or may not include an altitude component (e.g., height abovesea level, height above or depth below ground level, floor level orbasement level). Alternatively, a location of the UE 105 may beexpressed as a civic location (e.g., as a postal address or thedesignation of some point or small area in a building such as aparticular room or floor). A location of the UE 105 may also beexpressed as an area or volume (defined either geodetically or in civicform) within which the UE 105 is expected to be located with someprobability or confidence level (e.g., 67%, 95%, etc.). A location ofthe UE 105 may further be a relative location comprising, for example, adistance and direction or relative X, Y (and Z) coordinates definedrelative to some origin at a known location which may be definedgeodetically, in civic terms, or by reference to a point, area, orvolume indicated on a map, floor plan or building plan. In thedescription contained herein, the use of the term location may compriseany of these variants unless indicated otherwise. When computing thelocation of a UE, it is common to solve for local X, Y, and possibly Zcoordinates and then, if needed, convert the local coordinates intoabsolute ones (e.g. for latitude, longitude and altitude above or belowmean sea level).

Base stations in the NG-RAN 235 shown in FIG. 2 may correspond to basestations 120 in FIG. 1 and may include NR NodeB (gNB) 210-1 and 210-2(collectively and generically referred to herein as gNBs 210). Pairs ofgNBs 210 in NG-RAN 235 may be connected to one another (e.g., directlyas shown in FIG. 2 or indirectly via other gNBs 210). Access to the 5Gnetwork is provided to UE 105 via wireless communication between the UE105 and one or more of the gNBs 210, which may provide wirelesscommunications access to the 5G CN 240 on behalf of the UE 105 using 5GNR. 5G NR radio access may also be referred to as NR radio access or as5G radio access. In FIG. 2, the serving gNB for UE 105 is assumed to begNB 210-1, although other gNBs (e.g. gNB 210-2) may act as a serving gNBif UE 105 moves to another location or may act as a secondary gNB toprovide additional throughput and bandwidth to UE 105.

Base stations in the NG-RAN 235 shown in FIG. 2 may also or insteadinclude a next generation evolved Node B, also referred to as an ng-eNB,214. Ng-eNB 214 may be connected to one or more gNBs 210 in NG-RAN235—e.g. directly or indirectly via other gNBs 210 and/or other ng-eNBs.An ng-eNB 214 may provide LTE wireless access and/or evolved LTE (eLTE)wireless access to UE 105. Some gNBs 210 (e.g. gNB 210-2) and/or ng-eNB214 in FIG. 2 may be configured to function as positioning-only beaconswhich may transmit signals (e.g., Positioning Reference Signal (PRS))and/or may broadcast assistance data to assist positioning of UE 105 butmay not receive signals from UE 105 or from other UEs. It is noted thatwhile only one ng-eNB 214 is shown in FIG. 2, some embodiments mayinclude multiple ng-eNBs 214. Base stations 210, 214 may communicatedirectly with one another via an Xn communication interface.Additionally or alternatively, base stations 210, 214 may communicatedirectly or indirectly with other components of the 5G NR positioningsystem 200, such as the LMF 220 and AMF 215.

5G NR positioning system 200 may also include one or more WLANs 216which may connect to a Non-3GPP InterWorking Function (N3IWF) 250 in the5G CN 240 (e.g., in the case of an untrusted WLAN 216). For example, theWLAN 216 may support IEEE 802.11 Wi-Fi access for UE 105 and maycomprise one or more Wi-Fi APs (e.g., APs 130 of FIG. 1). Here, theN3IWF 250 may connect to other elements in the 5G CN 240 such as AMF215. In some embodiments, WLAN 216 may support another RAT such asBluetooth. The N3IWF 250 may provide support for secure access by UE 105to other elements in 5G CN 240 and/or may support interworking of one ormore protocols used by WLAN 216 and UE 105 to one or more protocols usedby other elements of 5G CN 240 such as AMF 215. For example, N3IWF 250may support IPSec tunnel establishment with UE 105, termination ofIKEv2/IPSec protocols with UE 105, termination of N2 and N3 interfacesto 5G CN 240 for control plane and user plane, respectively, relaying ofuplink (UL) and downlink (DL) control plane Non-Access Stratum (NAS)signaling between UE 105 and AMF 215 across an N1 interface. In someother embodiments, WLAN 216 may connect directly to elements in 5G CN240 (e.g. AMF 215 as shown by the dashed line in FIG. 2) and not viaN3IWF 250. For example, direct connection of WLAN 216 to 5GCN 240 mayoccur if WLAN 216 is a trusted WLAN for 5GCN 240 and may be enabledusing a Trusted WLAN Interworking Function (TWIF) (not shown in FIG. 2)which may be an element inside WLAN 216. It is noted that while only oneWLAN 216 is shown in FIG. 2, some embodiments may include multiple WLANs216.

Access nodes may comprise any of a variety of network entities enablingcommunication between the UE 105 and the AMF 215. This can include gNBs210, ng-eNB 214, WLAN 216, and/or other types of cellular base stations.However, access nodes providing the functionality described herein mayadditionally or alternatively include entities enabling communicationsto any of a variety of RATs not illustrated in FIG. 2, which may includenon-cellular technologies. Thus, the term “access node,” as used in theembodiments described herein below, may include but is not necessarilylimited to a gNB 210, ng-eNB 214 or WLAN 216.

In some embodiments, an access node, such as a gNB 210, ng-eNB 214, orWLAN 216 (alone or in combination with other components of the 5G NRpositioning system 200), may be configured to, in response to receivinga request for location information from the LMF 220, obtain locationmeasurements of uplink (UL) signals received from the UE 105) and/orobtain downlink (DL) location measurements from the UE 105 that wereobtained by UE 105 for DL signals received by UE 105 from one or moreANs. As noted, while FIG. 2 depicts access nodes 210, 214, and 216configured to communicate according to 5G NR, LTE, and Wi-Ficommunication protocols, respectively, access nodes configured tocommunicate according to other communication protocols may be used, suchas, for example, a Node B using a Wideband Code Division Multiple Access(WCDMA) protocol for a Universal Mobile Telecommunications Service(UMTS) Terrestrial Radio Access Network (UTRAN), an eNB using an LTEprotocol for an Evolved UTRAN (E-UTRAN), or a Bluetooth® beacon using aBluetooth protocol for a WLAN. For example, in a 4G Evolved PacketSystem (EPS) providing LTE wireless access to UE 105, a RAN may comprisean E-UTRAN, which may comprise base stations comprising eNBs supportingLTE wireless access. A core network for EPS may comprise an EvolvedPacket Core (EPC). An EPS may then comprise an E-UTRAN plus an EPC,where the E-UTRAN corresponds to NG-RAN 235 and the EPC corresponds to5GCN 240 in FIG. 2. The methods and techniques described herein forobtaining a civic location for UE 105 may be applicable to such othernetworks.

The gNBs 210 and ng-eNB 214 can communicate with an AMF 215, which, forpositioning functionality, communicates with an LMF 220. The AMF 215 maysupport mobility of the UE 105, including cell change and handover of UE105 from an access node 210, 214, or 216 of a first RAT to an accessnode 210, 214, or 216 of a second RAT. The AMF 215 may also participatein supporting a signaling connection to the UE 105 and possibly data andvoice bearers for the UE 105. The LMF 220 may support positioning of theUE 105 using a CP location solution when UE 105 accesses the NG-RAN 235or WLAN 216 and may support position procedures and methods, includingUE assisted/UE based and/or network based procedures/methods, such asAssisted GNSS (A-GNSS), Observed Time Difference Of Arrival (OTDOA)(which may be referred to in NR as Time Difference Of Arrival (TDOA) orDL-TDOA), Real Time Kinematic (RTK), Precise Point Positioning (PPP),Differential GNSS (DGNSS), Enhance Cell ID (ECID), angle of arrival(AOA), angle of departure (AOD), WLAN positioning, round trip signalpropagation delay (RTT), multi-cell RTT, and/or other positioningprocedures and methods. The LMF 220 may also process location servicerequests for the UE 105, e.g., received from the AMF 215 or from theGMLC 225. The LMF 220 may be connected to AMF 215 and/or to GMLC 225. Insome embodiments, a network such as 5GCN 240 may additionally oralternatively implement other types of location-support modules, such asan Evolved Serving Mobile Location Center (E-SMLC) or a SUPL LocationPlatform (SLP). It is noted that in some embodiments, at least part ofthe positioning functionality (including determination of a UE 105'slocation) may be performed at the UE 105 (e.g., by measuring downlinkPRS (DL-PRS) signals transmitted by wireless nodes such as gNBs 210,ng-eNB 214 and/or WLAN 216, and/or using assistance data provided to theUE 105, e.g., by LMF 220).

The Gateway Mobile Location Center (GMLC) 225 may support a locationrequest for the UE 105 received from an external client 230 and mayforward such a location request to the AMF 215 for forwarding by the AMF215 to the LMF 220. A location response from the LMF 220 (e.g.,containing a location estimate for the UE 105) may be similarly returnedto the GMLC 225 either directly or via the AMF 215, and the GMLC 225 maythen return the location response (e.g., containing the locationestimate) to the external client 230.

A Network Exposure Function (NEF) 245 may be included in 5GCN 240. TheNEF 245 may support secure exposure of capabilities and eventsconcerning 5GCN 240 and UE 105 to the external client 230, which maythen be referred to as an Access Function (AF) and may enable secureprovision of information from external client 230 to 5GCN 240. NEF 245may be connected to AMF 215 and/or to GMLC 225 for the purposes ofobtaining a location (e.g. a civic location) of UE 105 and providing thelocation to external client 230.

As further illustrated in FIG. 2, the LMF 220 may communicate with thegNBs 210 and/or with the ng-eNB 214 using an NR Positioning Protocol A(NRPPa) as defined in 3GPP Technical Specification (TS) 38.445. NRPPamessages may be transferred between a gNB 210 and the LMF 220, and/orbetween an ng-eNB 214 and the LMF 220, via the AMF 215. As furtherillustrated in FIG. 2, LMF 220 and UE 105 may communicate using an LTEPositioning Protocol (LPP) as defined in 3GPP TS 37.355. Here, LPPmessages may be transferred between the UE 105 and the LMF 220 via theAMF 215 and a serving gNB 210-1 or serving ng-eNB 214 for UE 105. Forexample, LPP messages may be transferred between the LMF 220 and the AMF215 using messages for service-based operations (e.g., based on theHypertext Transfer Protocol (HTTP)) and may be transferred between theAMF 215 and the UE 105 using a 5G NAS protocol. The LPP protocol may beused to support positioning of UE 105 using UE assisted and/or UE basedposition methods such as A-GNSS, RTK, OTDOA, multi-cell RTT, AOD, and/orECID. The NRPPa protocol may be used to support positioning of UE 105using network based position methods such as ECID, AOA, uplink TDOA(UL-TDOA) and/or may be used by LMF 220 to obtain location relatedinformation from gNBs 210 and/or ng-eNB 214, such as parameters definingDL-PRS transmission from gNBs 210 and/or ng-eNB 214.

In the case of UE 105 access to WLAN 216, LMF 220 may use NRPPa and/orLPP to obtain a location of UE 105 in a similar manner to that justdescribed for UE 105 access to a gNB 210 or ng-eNB 214. Thus, NRPPamessages may be transferred between a WLAN 216 and the LMF 220, via theAMF 215 and N3IWF 250 to support network-based positioning of UE 105and/or transfer of other location information from WLAN 216 to LMF 220.Alternatively, NRPPa messages may be transferred between N3IWF 250 andthe LMF 220, via the AMF 215, to support network-based positioning of UE105 based on location related information and/or location measurementsknown to or accessible to N3IWF 250 and transferred from N3IWF 250 toLMF 220 using NRPPa. Similarly, LPP and/or LPP messages may betransferred between the UE 105 and the LMF 220 via the AMF 215, N3IWF250, and serving WLAN 216 for UE 105 to support UE assisted or UE basedpositioning of UE 105 by LMF 220.

In a 5G NR positioning system 200, positioning methods can becategorized as being “UE assisted” or “UE based.” This may depend onwhere the request for determining the position of the UE 105 originated.If, for example, the request originated at the UE (e.g., from anapplication, or “app,” executed by the UE), the positioning method maybe categorized as being UE based. If, on the other hand, the requestoriginates from an external client or AF 230, LMF 220, or other deviceor service within the 5G network, the positioning method may becategorized as being UE assisted (or “network-based”).

With a UE-assisted position method, UE 105 may obtain locationmeasurements and send the measurements to a location server (e.g., LMF220) for computation of a location estimate for UE 105. ForRAT-dependent position methods location measurements may include one ormore of a Received Signal Strength Indicator (RSSI), Round Trip signalpropagation Time (RTT), Reference Signal Received Power (RSRP),Reference Signal Received Quality (RSRQ), Reference Signal TimeDifference (RSTD), Time of Arrival (TOA), AOA, Receive Time-TransmissionTime Difference (Rx-Tx), Differential AOA (DAOA), AOD, or Timing Advance(TA) for gNBs 210, ng-eNB 214, and/or one or more access points for WLAN216. Additionally or alternatively, similar measurements may be made ofsidelink signals transmitted by other UEs, which may serve as anchorpoints for positioning of the UE 105 if the positions of the other UEsare known. The location measurements may also or instead includemeasurements for RAT-independent positioning methods such as GNSS (e.g.,GNSS pseudorange, GNSS code phase, and/or GNSS carrier phase for GNSSsatellites 110), WLAN, etc.

With a UE-based position method, UE 105 may obtain location measurements(e.g., which may be the same as or similar to location measurements fora UE assisted position method) and may further compute a location of UE105 (e.g., with the help of assistance data received from a locationserver such as LMF 220, an SLP, or broadcast by gNBs 210, ng-eNB 214, orWLAN 216).

With a network based position method, one or more base stations (e.g.,gNBs 210 and/or ng-eNB 214), one or more APs (e.g., in WLAN 216), orN3IWF 250 may obtain location measurements (e.g., measurements of RSSI,RTT, RSRP, RSRQ, AOA, or TOA) for signals transmitted by UE 105, and/ormay receive measurements obtained by UE 105 or by an AP in WLAN 216 inthe case of N3IWF 250, and may send the measurements to a locationserver (e.g., LMF 220) for computation of a location estimate for UE105.

Positioning of the UE 105 also may be categorized as UL, DL, or DL-ULbased, depending on the types of signals used for positioning. If, forexample, positioning is based solely on signals received at the UE 105(e.g., from a base station or other UE), the positioning may becategorized as DL based. On the other hand, if positioning is basedsolely on signals transmitted by the UE 105 (which may be received by abase station or other UE, for example), the positioning may becategorized as UL based. Positioning that is DL-UL based includespositioning, such as RTT-based positioning, that is based on signalsthat are both transmitted and received by the UE 105.

Depending on the type of positioning (e.g., UL, DL, or DL-UL based) thetypes of reference signals used can vary. For DL-based positioning, forexample, these signals may comprise PRS (e.g., DL-PRS transmitted bybase stations or SL-PRS transmitted by other UEs), which can be used forOTDOA, AOD, and RTT measurements. Other reference signals that can beused for positioning (UL, DL, or DL-UL) may include Sounding ReferenceSignal (SRS), Channel State Information Reference Signal (CSI-RS),synchronization signals (e.g., synchronization signal block (SSB)Synchronizations Signal (SS)), Physical Uplink Control Channel (PUCCH),Physical Uplink Shared Channel (PUSCH), Physical Sidelink Shared Channel(PSSCH), Demodulation Reference Signal (DMRS), etc. Moreover, referencesignals may be transmitted in a Tx beam and/or received in an Rx beam(e.g., using beamforming techniques), which may impact angularmeasurements, such as AOD and/or AOA.

FIG. 3 is an illustration how TDOA-based positioning can be made,according to some embodiments. In brief, TDOA-based positioning ispositioning made based on known positions of TRPs (e.g., TRPs 310-1,310-2, and 310-3, collectively and generically referred to herein asTRPs 310), known times at which TRPs transmit respective referencesignals (e.g., PRS), and differences in times at which the UE 105receives the reference signals from each TRP. Again, a TRP maycorrespond with a base station, such as base stations 120 of FIG. 1. Ina 5G NR positioning system 200, a TRP may include a gNB 210 and/orng-eNB 214, as illustrated in FIG. 2.

In TDOA-based positioning, a location server may provide TDOA assistancedata to a UE P105 for a reference TRP (which may be called a “referencecell” or “reference resource”), and one or more neighboring TRPs (whichmay be called “neighbor cells” or “neighboring cells”, and whichindividually may be called a “target cell” or “target resource”)relative to the reference TRP. For example, the assistance data mayprovide the center channel frequency of each TRP, various PRSconfiguration parameters (e.g., N_(PRS), T_(PRS), muting sequence,frequency hopping sequence, PRS ID, PRS bandwidth), a TRP (cell) globalID, PRS signal characteristics associated with a directional PRS, and/orother TRP related parameters applicable to TDOA or some other positionmethod. TDOA-based positioning by a UE 105 may be facilitated byindicating the serving TRP for the UE 105 in the TDOA assistance data(e.g., with the reference TRP indicated as being the serving TRP). Insome aspects, TDOA assistance data may also include “expected ReferenceSignal Time Difference (RSTD)” parameters, which provide the UE 105 withinformation about the RSTD values the UE 105 is expected to measure atits current location between the reference TRP and each neighbor TRP,together with an uncertainty of the expected RSTD parameter. Theexpected RSTD, together with the associated uncertainty, may define asearch window for the UE 105 within which the UE 105 is expected tomeasure the RSTD value. TDOA assistance information may also include PRSconfiguration information parameters, which allow a UE 105 to determinewhen a PRS positioning occasion occurs on signals received from variousneighbor TRPs relative to PRS positioning occasions for the referenceTRP, and to determine the PRS sequence transmitted from various TRPs inorder to measure a time of arrival (TOA) or RSTD. TOA measurements maybe RSRP (Reference Signal Receive Power) measurements of average powerof Resource Elements (RE) that carry PRS (or other reference signals).

Using the RSTD measurements, the known absolute or relative transmissiontiming of each TRP, and the known position(s) of wireless node physicaltransmitting antennas for the reference and neighboring TRPs, the UEposition may be calculated (e.g., by the UE 105 or by a locationserver). More particularly, the RSTD for a neighbor TRP “k” relative toa reference TRP “Ref,” may be given as the difference in TOAmeasurements of signals from each TRP (i.e., TOA_(k)−TOA_(Ref)), wherethe TOA values may be measured modulo one subframe duration (1 ms) toremove the effects of measuring different subframes at different times.In FIG. 3, for example, a first TRP 310-1 may be designated as thereference TRP, and second and third TRPs (P110-2 and 310-3) are neighborTRPs. If UE 105 receives reference signals from first TRP 310-1, secondTRP 310-2, and third TRP 310-3 at times T1, T2, and T2, respectively,then the RSTD measurement for second TRP 310-2 would be determined asT2−T1 and the RSTD measurement for third TRP 310-3 would be determinedas T3−T1. RSTD measurements can be used by the UE 105 and/or sent to alocation server to determine the location of the UE 105 using (i) theRSTD measurements, (ii) the known absolute or relative transmissiontiming of each TRP, (iii) the known position(s) of TRPs 310 for thereference and neighboring TRPs, and/or (iv) directional PRScharacteristics such as a direction of transmission. Geometrically,information (i)-(iv) allows for possible locations of the UE 105 to bedetermined for each RSTD (where each RSTD results in a hyperbola, asshown in FIG. 3), and the position of the UE 105 to be determined fromthe intersection of the possible locations for all RSTDs.

FIG. 4 is an illustration how RTT-based positioning (or multi-RTT) canbe made, according to some embodiments. In brief, RTT-based positioningincludes positioning methods in which the position of the UE 105 isdetermined based on known positions of TRPs (e.g., TRPs 410, which againmay correspond to gNBs 210 and/or ng-eNB 214 of FIG. 2) and knowndistances between the UE 105 and the TRPs. RTT measurements between theUE 105 and each TRP are used to determine a distance between the UE 105and the respective TRP, and multilateration can be used to determine thelocation of the UE 105.

In RTT-based positioning, a location server may coordinate RTTmeasurements between the UE 105 and each TRP. Information provided tothe UE 105 may be included in RTT assistance data. This can include, forexample, reference signal (e.g., PRS) timing and other signalcharacteristics, TRP (cell) ID, and/or other cell related parametersapplicable to multi-RTT or some other position method. Depending ondesired functionality, RTT measurements may be made (and initiated by)the UE 105 or a TRP 410.

RTT measurements measure distance using Over The Air (OTA) delay. Aninitiating device (e.g., the UE 105 or a TRP 410) transmits a firstreference signal at first time, T1, which propagates to a respondingdevice. At a second time, T2, the first reference signal arrives at theresponding device. The OTA delay (i.e., the propagation time it takesfor the first reference signal to travel from the initiating device tothe responding device) is the difference between T1 and T2. Theresponding device then transmits a second reference signal at a thirdtime, T3, and the second reference signal is received and measured bythe initiating device at a fourth time, T4. RSRP measurements may beused to determine TOA for times T2 and T4. Distance, d, between theinitiating and responding devices therefore can be determined using thefollowing equation:

$\begin{matrix}{\frac{2d}{c} = {{\left( {T_{4} - T_{1}} \right) - \left( {T_{3} - T_{2}} \right)} = {\left( {T_{4} - T_{1}} \right) + {\left( {T_{2} - T_{3}} \right).}}}} & (1)\end{matrix}$

(As will be appreciated, distance, d, divided by the speed of RFpropagation, c, equals the OTA delay.) Thus, a precise determination ofthe distance between the initiating device and responding device can bemade.

RTT measurements between the UE 105 and TRPs 410 can therefore allow theposition of the UE 105 to be determined using multilateration. That is,RTT measurements between the UE 105 and the first TRP 410-1, second TRP210-2, and third TRP 410-3 (RTT measurements RTT1, RTT2, and RTT3,respectively) result in a determination of the distance of the UE 105from each of the TRPs 410. These distances can be used to trace circlesaround known positions of the TRPs 410 (where Circle1 corresponds to TRP410-1, Circle2 corresponds to TRP 410-2, and Circle3 corresponds to TRP410-3.) The position of the UE 105 can be determined as the intersectionbetween the circles.

FIG. 5 is a simplified diagram illustrating how an anchor UE 505 can beused in the positioning of a target UE 503 in a 5G NR network, accordingto an embodiment. Here, arrows between the various components illustratecommunication links. As illustrated in FIG. 2, this may involve wirelessand/or wired communication technologies and may include one or moreintermediary components. TRPs 510-1, 510-2, 510-3, and 510-4 may bereferred to collectively or generically referred to as TRP(s) 510. Forsimplicity, a single anchor UE 505 is illustrated. However, althoughonly one anchor UE 505 may be used in some instances, other instancesmay use two or more. Moreover, in some instances, anchor UEs 505 maycomprise the only type of anchor point for positioning and/or TRPs 510may not be used as anchor points. (As used herein, the term “anchorpoint” refers to a device with a known location used to determine thelocation of the target UE 503.) Further, although anchor UE 505 andtarget UE 503 are illustrated as having separate serving TRPs (TRP 510-4and TRP 510-1, respectively), embodiments are not so limited. In somescenarios, for example, target UE 503 and anchor UE 505 may share acommon serving TRP 510.

To determine the position of the target UE 503 (e.g., using any of thepreviously-described positioning techniques) the target UE 503 can takemeasurements of wireless signals sent from different anchor points: TRPs510-1 to 510-3 and anchor UE 505. The target UE 503 can communicate withand/or obtain measurements from TRP 510-1 to TRP 510-3 using a Uu(network) interface 530. Measurements may be made from reference signalsfrom the TRPs 510, such as PRS (e.g., DL-PRS). With regard to anchor UE505, target UE 503 can communicate using SL interface 550. As previouslynoted, and SL interface 550 allows direct (D2D) communication betweenthe target UE 503 and anchor UE 505, and may be used in a manner similarto the Uu interfaces 530, allowing the target UE 503 to obtainposition-related measurements in relation to determining the location ofthe target UE 503. As such, the anchor UE 505 may be configured toprovide a PRS (e.g., SL-PRS) and/or similar reference signal via the SLinterface 550, which may be transmitted in a manner similar to a TRP.For its part, the anchor UE 505 may also communicate with the LMF 220via TRP 510-4 using a Uu interface 530. As noted, TRP 510-4 may comprisethe serving TRP for anchor UE 505 in this example.

The use of an anchor UE 505 in the positioning of the target UE 503 issimilar to the use of base stations in FIGS. 3 and 5 for TDOA-based andRTT-based positioning. The use of anchor UEs 505 in this manner can bebeneficial, providing additional accuracy to a position estimate of thetarget UE 503 and/or enabling for a threshold number of anchor points incases where the target UE 503 is unable to communicate with a sufficientnumber of TRPs 510 for positioning (e.g., fewer than three). However, asnoted, an anchor UE 505 may be subject to a Timing Advance (TA) commandwhich, if received and applied during a positioning session of thetarget UE 503, can impact the timing of the transmission of SL-PRS viathe SL interface 550. This can, in turn, impact the reliability andaccuracy of the position estimate for the target UE 503.

TA is used to control the uplink transmission timing of a UE. This canhelp ensure UE transmissions from multiple UEs are synchronized with aserving TRP when the transmissions are received by the serving TRP. Tomaintain this synchronization, the serving TRP can issue TA commands toa UE to cause the UE to make TA adjustments to stay in synchronization.These TA commands can be issued by the TRP, for example, when thepropagation delay between the UE and TRP changes, which can result frommovement by the UE. Although it is primarily applicable to PUSCH, PUCCH,and SRS signals, it can impact the transmission time of an SL-PRS ifreceived during an SL-PRS positioning session between UEs. Inparticular, an SL-PRS transmitted by an anchor UE 505 may include atimestamp to allow a target UE 503 or location server to accuratelycalculate an RTT or TDOA measurement based on the SL-PRS. However,TA-related adjustments may not be accurately reflected in timestamps andmay therefore result in inaccurate measurements and ultimately theinaccurate positioning of the target UE 503. FIGS. 6 and 7 illustratetwo examples.

FIG. 6 is a timing diagram illustrating an RTT exchange 600 between twoUEs, which may occur over an SL interface 550 (FIG. 5) during RTT-based,SL-assisted positioning of a UE. Here, UE 1 may correspond with a targetUE 503 and UE two may correspond with an anchor UE 505, but embodimentsare not so limited. Transmission/reception times T1-T4 correspond withthose previously described with respect to RTT-based positioning (e.g.,times T1-T4 in equation (1)). This RTT exchange 600 may occur during anSL-PRS positioning session between the UE 1 and UE 2. Timing and otheraspects of the RTT exchange 600 may be based on an SL-PRS configurationreceived by the UEs from a TRP and/or location server (e.g., LMF 220).

In this example, UE1 transmits a first SL-PRS 610 at time T1, which isreceived by UE2 at time T2. UE2 is configured to transmit a secondSL-PRS 620-1 at time T3, which would be received by UE1 at time T4.However, UE2 receives a TA command 630 that UE2 applies between times T2and T3. In this case, this causes a delay of A. Thus, rather thantransmitting the SL-PRS 620-1 at time T3, UE2 transmits an SL-PRS 620-2at time T3+A. It can be noted that, depending on the TA adjustment madeby UE2 in response to the TA command 630, A may not necessarily resultin a delay in the transmission of SL-PRS 620-2 as illustrated in FIG. 6.In other instances, for example, A could be a negative value resultingin an earlier transmission.

The value of A can lead to an inaccurate RTT measurement (and,resultantly, an inaccurate determination of distance between UE1 andUE2) if unaccounted for. In particular, A may be combined with clockdrift between T1 and T2, which can result in an inaccurate Rx-Txmeasurement by UE2 used to determine the RTT measurement. Thisinaccurate Rx-Tx measurement can, in turn, cause errors in thedetermination of a location for UE 1, for example.

Furthermore, accounting for A in the calculation of the RTT measurementmay not be straightforward. The RTT measurement may be calculated at UE1(e.g., using equation (1) above) or at a location server that receivestimes T1-T4 from UE1. However, TA commands are UE-specific, typicallyprovided to the UE by the UE's serving TRP via random access channel(RACH) response (e.g., during handover of the UE from one cell toanother) or via Medium Access Control (MAC) Control Element (CE)(MAC-CE). As such, UE1 and the location server are unaware of TAcommands received by UE2 and are thereby unable to account for TAadjustments during the RTT exchange 600.

FIG. 7 is a timing diagram illustrating a TDOA-based measurement 700using two UEs, similar to FIG. 6. Again, this may take place over an SLinterface 550 (FIG. 5) during TDOA-based, SL-assisted positioning of aUE. In this example, the TDOA-based measurement 700 is based on a seriesof SL-PRS transmitted by UE2 and received by UE1. However, aftertransmitting a SL-PRS 710 at time T1 and before transmitting a SL-PRS720-1 at time T2, UE2 receives a TA command 730. Similar to the RTTexchange 600 of FIG. 6, this causes a delay of A in the transmission ofSL-PRS 720-1 by UE2. Thus, rather than transmitting the SL-PRS 720-1 attime T2, UE2 transmits an SL-PRS 720-2 at time T2+A, and UE1 receives SLPRS 720-2 at TOA2+A. (Again, in some instances A could be a negativevalue resulting in an earlier transmission.) More generally, forTDOA-based positioning, such as TDOA-based measurement 700, applying aTA cannot only impact the transmission time of a single subsequentSL-PRS, but may impact all subsequent occasion times/repetitions of anSL-PRS. Similar to RTT-based positioning, this can cause inaccuracies inthe TDOA-based measurement and ultimately in the position estimate a UE.

Embodiments address these and other issues by allowing for a TA commandfor an anchor UE to be postponed or omitted until after the anchor UEconducts an SL-PRS positioning session with a target UE. Alternatively,embodiments may allow an anchor UE to report TA adjustments made duringan SL-PRS positioning session to a target UE or a location server toallow the target UE or location server to account for such TAadjustments when determining the position of the target UE. Adescription of an embodiment is provided hereinafter with regard to FIG.8.

FIG. 8 is a flow diagram of a method 800 of TA handling for SL-assistedpositioning of a first UE, according to an embodiment. Means forperforming the functionality illustrated in one or more of the blocksshown in FIG. 8 may be performed by hardware and/or software componentsof a UE (e.g., an anchor UE 505 of FIG. 5) or location server (e.g.,location server 160 of FIG. 1 or LMF 220 of FIG. 2). Example componentsof a UE are illustrated in FIG. 10, and example components of a computerserver are illustrated in FIG. 12, both of which are described in moredetail below.

The method 800 can begin with the functionality at block 810, whichcomprises determining the first UE is configured to transmit an SL-PRSto a second UE to perform the SL-assisted positioning. Thisdetermination can be made, for example, by the first UE itself, based onan SL-PRS configuration it receives from a location server or TRP toengage in an SL-PRS positioning session with the second UE (e.g., atarget UE 503). Alternatively, this determination may be made by thelocation server, upon configuring the first UE. As previously noted,SL-PRS can be used to make RTT and/or TDOA measurements with which theposition of the second UE may be estimated.

Means for performing the functionality at block 810 by a UE maycomprise, for example, a bus 1005, processing unit(s) 1010, digitalsignal processor (DSP) 1020, wireless communication interface 1030,memory 1060, and/or other components of a UE as illustrated in FIG. 10and described below. Means for performing the functionality at block 810by a location server may comprise, for example, a bus 1005, processingunit(s) 1210, working memory 1235, wireless communication interface1233, and/or other components of a computer system as illustrated inFIG. 12 and described below.

At block 820, the functionality comprises determining a length of timefor a guard period based on a configuration of the first UE fortransmitting the SL-PRS, wherein the guard period comprises a period oftime during which the SL-PRS is transmitted by the first UE. Morespecifically, a guard period may be defined as a period of time relatedto SL-assisted positioning of a target UE (e.g., the second UE) duringwhich, if a TA adjustment is applied, may degrade the accuracy of anySL-PRS-based measurements. It may include not only a window of timeduring which the SL-PRS is transmitted (which may include a series ofrepeated SL-PRS resources, as described with regard to the TDOA-basedmeasurement 700 of FIG. 7) but may also include additional time beforeand/or afterward to account for processing time, timer adjustmentbuffer, etc. According to some embodiments, the guard period may beselected from a table of enumerated values (e.g., 1, 2, 5, 10 ms, etc.)where, for example, the smallest value that provides sufficient time forthe positioning session and any additional time before and/or afterward.Thus, for example, if SL-PRS for a TDOA-based measurement is transmittedover the course of 20 ms and 4 ms of additional time is needed forprocessing, timer adjustment buffer, etc., then a 25 ms guard periodcould be selected as the length of the guard period if it is among theenumerated values for guard period lengths. Depending on desiredfunctionality, the guard period could be defined in terms of a number ofslots, symbols, and/or subframes of an orthogonal frequency-divisionmultiplexing (OFDM) communication scheme (such as the OFDM schemeimplemented by LTE and 5G), and/or may simply be defined in terms oflength of time.

Means for performing the functionality at block 820 by a UE maycomprise, for example, a bus 1005, processing unit(s) 1010, digitalsignal processor (DSP) 1020, memory 1060, and/or other components of aUE as illustrated in FIG. 10 and described below. Means for performingthe functionality at block 820 by a location server may comprise, forexample, a bus 1005, processing unit(s) 1210, working memory 1235,and/or other components of a computer system as illustrated in FIG. 12and described below.

The functionality at block 830 comprises sending, to a serving TRP ofthe first UE, a message indicating the guard period and comprising aTA-related request, wherein the TA-related request includes a request topostpone applying a TA command received by the first UE until after theguard period, or a request for the serving TRP not to send a TA commandto the first UE during the guard period. These two different types ofrequests are reflective of two different types of scenarios.

In a first scenario, the first UE receives a TA command from its servingTRP before or during an SL-PRS positioning session that is to be appliedduring the SL-PRS positioning session. According to some embodiments,therefore, the functionality of method 800 may be in response to a TAcommand received by the first UE during the SL-PRS positioning session.As such, any resulting TA adjustment from applying the TA command mayinterfere with the timing of the transmission of the SL-PRS.Accordingly, in such instances, the first UE can send the serving TRP arequest to postpone the application of the TA command until after theguard period. In this first scenario, the TA-related request maytherefore comprise the request to postpone applying the TA commandreceived by the first UE until after the guard period, and the messageis sent by the first UE, during a SL-PRS positioning session duringwhich the SL-PRS is transmitted by the first UE to the second UE.Because the SL-PRS positioning session may be partially complete, thedetermination of the guard period may be impacted. As such, thedetermining the length of time for the guard period (the functionalityat block 820) may further be based on her remaining amount of time inthe SL-PRS positioning session.

The way in which the message is sent in this first scenario may vary,depending on desired functionality. According to some embodiments, forexample, sending the message comprises including the message in UCI(Uplink Control Information), a Radio Resource Control (RRC) message, ora Medium Access Control (MAC) Control Element (CE), or any combinationthereof.

In this first scenario, the method 800 may include additional steps ifpostponement is granted. For example, according to some embodiments, themethod 800 may further comprise receiving, at the first UE, anindication from the serving TRP of an acceptance of the TA-relatedrequest and postponing the applying of the TA command received by thefirst UE until after the guard period. As described in more detailbelow, the serving TRP may grant or deny the postponement based on anapplicable TA priority condition. That is, if the serving TRP determinesthe TA command should be applied to help ensure a high-priority processis executed smoothly, the serving TRP can deny the request. If therequest is denied, the first UE can apply the TA command. As describedin further detail below, according to some embodiments, the first UE mayprovide a network node (e.g., the second UE or the location server) withinformation regarding the TA adjustment to allow the network node toaccount for the adjustment when determining the location of the secondUE.

In a second scenario, the TA-related request comprises the request forthe serving TRP not to send the TA command to the first UE during theguard period and the message is sent by a location server or the firstUE prior to an SL-PRS positioning session during which the SL-PRS istransmitted by the first UE to the second UE. In this scenario, therequest can include a starting time and duration of the guard period.Again, the first UE can communicate this information to the serving TRPusing UCI, and RRC message, a MAC-CE message, or the like. The locationserver can communicate this information to the serving TRP via NRPPa ora similar communication link.

Means for performing the functionality at block 830 by a UE maycomprise, for example, a bus 1005, processing unit(s) 1010, digitalsignal processor (DSP) 1020, wireless communication interface 1030,memory 1060, and/or other components of a UE as illustrated in FIG. 10and described below. Means for performing the functionality at block 830by a location server may comprise, for example, a bus 1005, processingunit(s) 1210, working memory 1235, wireless communication interface1233, and/or other components of a computer system as illustrated inFIG. 12 and described below.

The way in which the serving TRP processes the request can vary,depending on desired functionality. According to some embodiments, theserving TRP may provide an acknowledgment (or ACK) response to themessage, confirming that the TA-related request is granted. And thefirst UE will not receive a TA command, or a previously-received TAcommand, can be postponed accordingly. On the other hand, the servingTRP may reject the request with a negative acknowledgment (or NACK)response to the message. In the case of a rejection of a request topostpone a previously-received TA command, the first UE would apply theTA command without postponement. In the case of a rejection of a requestnot to receive a TA command during the guard period, the first UE orlocation server would be on notice that a TA command could be receivedduring the guard. That is, the serving TRP may or may not issue a TAcommand during the guard period; there may be no guarantees one way orthe other. Accordingly, according some embodiments of the method 800 mayfurther comprise receiving, at the first UE, a response to the messagefrom the serving TRP, wherein the response is indicative of a rejectionof the TA-related request. These embodiments may further comprisereceiving, at the first UE, a TA command from the serving TRP during theguard period and applying the TA command during the guard period.

Embodiments may respond to the application of a TA command during anSL-PRS positioning session in a variety of ways, depending on desiredfunctionality. According to some embodiments, the first UE may simplycancel the SL-PRS positioning session. Alternatively, embodiments mayaccount for a TA adjustment made from the application of the TA command.In particular, in cases where a serving TRP rejects a TA-related request(e.g., sent using the method 800) and/or as feature that may beindependent of a TA-related request, the first UE may track and recordits own time adjustment (e.g., the value of A in FIGS. 6 and/or 7). Thisinformation can be used to correct the PRS measurements.

The type of information the first UE can track and report may vary. Forexample, according to some embodiments, the first UE can determine whichSL-PRS occasions are impacted by the TA adjustment and send anindication of the impacted occasions (e.g., using a PRS resource ID andoccasion times), as well as how they were impacted (e.g., the value ofA).

Embodiments may account for different types of TA adjustments. That is,TA commands may result in a single-step adjustment in which all SL-PRSoccasions following the adjustment are impacted by the same amount. Thatis, the value of A is the same for all occasions. Alternatively, someadjustments may be gradual over time, increasing until the fulladjustment is reached. In other words, the value of A graduallyincreases to a desired value, which may result in a different value of Afor different SL-PRS occasions. As such, according to some embodiments,the first UE may indicate, in the report, how different occasions areimpacted differently.

The network node to which of the first UE provides the report may vary,depending on the circumstances. For example, for UE-based positioning inwhich the second UE (the target UE) determines its own position based onSL-PRS measurements (e.g., RTT-based or OTDOA-based measurements ofSL-PRS), the first UE may provide the report to the second UE. This canbe sent directly to the second UE using the SL interface (e.g., SLinterface 550 of FIG. 5). In these instances, the second UE can use theinformation in the reports to account for the TA adjustment inestimating its position. The TA adjustment may be accounted for, forexample, by using the value of the adjustment (A) to correct the PRSmeasurement or by determining a level of uncertainty of the PRSmeasurement based on the value of the adjustment.

Additionally or alternatively, for UE-assisted positioning in which thefirst and/or second UEs provide information (e.g., as assistance data ora PRS measurement report) to a location server to determine theestimated position of the second UE, the first UE can provide a reportto the location server. This can be done via LPP, for example, using aUu interface (e.g., Uu interface 530 of FIG. 5). Alternatively, this canbe done indirectly via the second UE, in which case the first UE wouldprovide the report to the second UE via an SL interface, and the secondUE would relay the report to the location server via a Uu interface. (Inthis case, the second UE may relay positioning-related information fromother UEs, which may be used to make similar SL-PRS measurements.) Ineither case, the location server can use the information in the reportto account for a TA adjustment when determining the estimated positionof the second UE.

Returning to FIG. 8, the method 800 may therefore provide thisfunctionality in instances in which the TA-related request at block 830is rejected by the serving TRP. Alternative embodiments of the method800 may therefore comprise receiving, at the first UE, a response to themessage from the serving TRP, where the response is indicative of arejection of the TA-related request, receiving, at the first UE, a TAcommand from the serving TRP during the guard period, and applying theTA command during the guard period. Embodiments may further comprisesending, from the first UE, a report to a network node, wherein thereport comprises a time adjustment of a transmission time of the SL-PRSbased on applying the TA command during the guard period, and a PRSresource identifier (ID) of the SL-PRS.

As noted, the serving TRP may use an applicable TA priority conditionwhen determining whether to grant or reject the TA-related request fromthe location server or first UE. This process is described in furtherdetail with regard to FIG. 9.

FIG. 9 is a flow diagram of a method 900 of TA handling for SL-assistedpositioning of a first UE, according to an embodiment, which can beperformed by the serving TRP of the first UE. As such, means forperforming the functionality illustrated in one or more of the blocksshown in FIG. 9 may be performed by hardware and/or software componentsof a TRP. Example components of a TRP are illustrated in FIG. 11, whichare described in more detail below.

The method 900 can begin with the functionality at block 910, whichcomprises receiving, at a serving TRP of the first UE, a message from anetwork node, the message indicating a guard period and comprising aTA-related request, wherein: the guard period comprises a period of timeduring which an SL-PRS is transmitted by the first UE to a second UE.The TA-related request comprises: a request to postpone applying a TAcommand received by the first UE until after the guard period, or arequest for the serving TRP not to send a TA command to the first UEduring the guard period. Here, the functionality at block 910 maycomprise the functionality of the serving TRP when receiving theinformation sent in block 830 of FIG. 8. As such, the guard period,TA-related request, and other aspects may correspond to those previouslydescribed. Moreover, as noted, the request may come from differentsources depending on circumstances. Thus, according to some embodiments,the network node comprises the first UE or a location server.

Means for performing the functionality at block 910 by a TRP maycomprise, for example, a bus 1105, processing unit(s) 1110, digitalsignal processor (DSP) 1120, wireless communication interface 1130,memory 1160, network interface 1180, and/or other components of a UE asillustrated in FIG. 11 and described below.

At block 920, the functionality comprises determining a response to themessage based on an applicable TA priority condition. As discussedpreviously, the serving TRP can choose whether to grant or deny/reject arequest based on whether or not other functions may be impacted by adelay in applying a TA command by the first UE. In implementation,priority rules for granting or rejecting a TA-related request related toSL-PRS positioning of a UE in view of TA priority conditions may beincluded in applicable communication standards, allowing the serving TRPto implement these priority rules upon receiving a TA-related request.

A TA priority condition comprises a condition that could be impacted bygranting the TA-related request. This can include, for example,high-priority conditions such as handover of the first UE between cells(e.g., designating a different serving TRP), high-prioritycommunications (e.g., mission-critical or Ultra-Reliable Low-LatencyCommunication (URLLC) communications). According to some embodiments,therefore, if the applicable TA priority condition includes either (orboth) of these conditions (the first UE being engaged in a handoverprocedure or the first UE engaged in high-priority medications), thenthe serving TRP may reject the TA-related request. Otherwise, theserving TRP may accept the TA-related request.

Means for performing the functionality at block 920 by a TRP maycomprise, for example, a bus 1105, processing unit(s) 1110, digitalsignal processor (DSP) 1120, memory 1160, and/or other components of aUE as illustrated in FIG. 11 and described below.

At block 930, the functionality comprises sending the response to thenetwork node. As previously noted, the response may be either indicativeof a rejection of TA-related request, or indicative of an acceptance ofTA-related request TA-related request. Moreover, the response may be inthe form of an ACK or NACK response to the message received at block910.

Means for performing the functionality at block 930 by a TRP maycomprise, for example, a bus 1105, processing unit(s) 1110, digitalsignal processor (DSP) 1120, wireless communication interface 1130,memory 1160, network interface 1180, and/or other components of a UE asillustrated in FIG. 11 and described below.

FIG. 10 illustrates an embodiment of a UE 1000, which can be utilized asdescribed herein above (e.g., in association with FIGS. 1-9) and maycorrespond with UE 105, target UE 503, anchor UE 505, UE1 and/or UE2.For example, the UE 1000 can perform one or more of the functions of themethod shown in FIG. 8. It should be noted that FIG. 10 is meant only toprovide a generalized illustration of various components, any or all ofwhich may be utilized as appropriate. It can be noted that, in someinstances, components illustrated by FIG. 10 can be localized to asingle physical device and/or distributed among various networkeddevices, which may be disposed at different physical locations.Furthermore, as previously noted, the functionality of the UE discussedin the previously described embodiments may be executed by one or moreof the hardware and/or software components illustrated in FIG. 10.

The UE 1000 is shown comprising hardware elements that can beelectrically coupled via a bus 1005 (or may otherwise be incommunication, as appropriate). The hardware elements may include aprocessing unit(s) 1010 which can include without limitation one or moregeneral-purpose processors, one or more special-purpose processors (suchas DSP chips, graphics acceleration processors, application specificintegrated circuits (ASICs), and/or the like), and/or other processingstructures or means. As shown in FIG. 10, some embodiments may have aseparate DSP 1020, depending on desired functionality. Locationdetermination and/or other determinations based on wirelesscommunication may be provided in the processing unit(s) 1010 and/orwireless communication interface 1030 (discussed below). The UE 1000also can include one or more input devices 1070, which can includewithout limitation one or more keyboards, touch screens, touch pads,microphones, buttons, dials, switches, and/or the like; and one or moreoutput devices 1015, which can include without limitation one or moredisplays (e.g., touch screens), light emitting diodes (LEDs), speakers,and/or the like.

The UE 1000 may also include a wireless communication interface 1030,which may comprise without limitation a modem, a network card, aninfrared communication device, a wireless communication device, and/or achipset (such as a Bluetooth® device, an IEEE 802.11 device, an IEEE802.15.4 device, a Wi-Fi device, a WiMAX device, a WAN device, and/orvarious cellular devices, etc.), and/or the like, which may enable theUE 1000 to communicate with other devices as described in theembodiments above. The wireless communication interface 1030 may permitdata and signaling to be communicated (e.g., transmitted and received)with TRPs of a network, for example, via eNBs, gNBs, ng-eNBs, accesspoints, various base stations and/or other access node types, and/orother network components, computer systems, and/or any other electronicdevices communicatively coupled with TRPs, as described herein. Thecommunication can be carried out via one or more wireless communicationantenna(s) 1032 that send and/or receive wireless signals 1034.According to some embodiments, the wireless communication antenna(s)1032 may comprise a plurality of discrete antennas, antenna arrays, orany combination thereof. The antenna(s) 1032 may be capable oftransmitting and receiving wireless signals using beams (e.g., Tx beamsand Rx beams). Beam formation may be performed using digital and/oranalog beam formation techniques, with respective digital and/or analogcircuitry. The wireless communication interface 1030 may include suchcircuitry.

Depending on desired functionality, the wireless communication interface1030 may comprise a separate receiver and transmitter, or anycombination of transceivers, transmitters, and/or receivers tocommunicate with base stations (e.g., ng-eNBs and gNBs) and otherterrestrial transceivers, such as wireless devices and access points.The UE 1000 may communicate with different data networks that maycomprise various network types. For example, a Wireless Wide AreaNetwork (WWAN) may be a CDMA network, a Time Division Multiple Access(TDMA) network, a Frequency Division Multiple Access (FDMA) network, anOrthogonal Frequency Division Multiple Access (OFDMA) network, aSingle-Carrier Frequency Division Multiple Access (SC-FDMA) network, aWiMAX (IEEE 802.16) network, and so on. A CDMA network may implement oneor more RATs such as CDMA2000, WCDMA, and so on. CDMA2000 includesIS-95, IS-2000 and/or IS-856 standards. A TDMA network may implementGSM, Digital Advanced Mobile Phone System (D-AMPS), or some other RAT.An OFDMA network may employ LTE, LTE Advanced, 5G NR, and so on. 5G NR,LTE, LTE Advanced, GSM, and WCDMA are described in documents from 3GPP.Cdma2000 is described in documents from a consortium named “3rdGeneration Partnership Project X3” (3GPP2). 3GPP and 3GPP2 documents arepublicly available. A wireless local area network (WLAN) may also be anIEEE 802.11x network, and a wireless personal area network (WPAN) may bea Bluetooth network, an IEEE 802.15x, or some other type of network. Thetechniques described herein may also be used for any combination ofWWAN, WLAN and/or WPAN.

The UE 1000 can further include sensor(s) 1040. Sensors 1040 maycomprise, without limitation, one or more inertial sensors and/or othersensors (e.g., accelerometer(s), gyroscope(s), camera(s),magnetometer(s), altimeter(s), microphone(s), proximity sensor(s), lightsensor(s), barometer(s), and the like), some of which may be used toobtain position-related measurements and/or other information.

Embodiments of the UE 1000 may also include a Global NavigationSatellite System (GNSS) receiver 1080 capable of receiving signals 1084from one or more GNSS satellites using an antenna 1082 (which could bethe same as antenna 1032). Positioning based on GNSS signal measurementcan be utilized to complement and/or incorporate the techniquesdescribed herein. The GNSS receiver 1080 can extract a position of theUE 1000, using conventional techniques, from GNSS satellites 110 of aGNSS system, such as Global Positioning System (GPS), Galileo, GLONASS,Quasi-Zenith Satellite System (QZSS) over Japan, IRNSS over India,BeiDou Navigation Satellite System (BDS) over China, and/or the like.Moreover, the GNSS receiver 1080 can be used with various augmentationsystems (e.g., a Satellite Based Augmentation System (SBAS)) that may beassociated with or otherwise enabled for use with one or more globaland/or regional navigation satellite systems, such as, e.g., Wide AreaAugmentation System (WAAS), European Geostationary Navigation OverlayService (EGNOS), Multi-functional Satellite Augmentation System (MSAS),and Geo Augmented Navigation system (GAGAN), and/or the like.

It can be noted that, although GNSS receiver 1080 is illustrated in FIG.10 as a distinct component, embodiments are not so limited. As usedherein, the term “GNSS receiver” may comprise hardware and/or softwarecomponents configured to obtain GNSS measurements (measurements fromGNSS satellites). In some embodiments, therefore, the GNSS receiver maycomprise a measurement engine executed (as software) by one or moreprocessing units, such as processing unit(s) 1010, DSP 1020, and/or aprocessing unit within the wireless communication interface 1030 (e.g.,in a modem). A GNSS receiver may optionally also include a positioningengine, which can use GNSS measurements from the measurement engine todetermine a position of the GNSS receiver using an Extended KalmanFilter (EKF), Weighted Least Squares (WLS), a hatch filter, particlefilter, or the like. The positioning engine may also be executed by oneor more processing units, such as processing unit(s) 1010 or DSP 1020.

The UE 1000 may further include and/or be in communication with a memory1060. The memory 1060 can include, without limitation, local and/ornetwork accessible storage, a disk drive, a drive array, an opticalstorage device, a solid-state storage device, such as a random accessmemory (RAM), and/or a read-only memory (ROM), which can beprogrammable, flash-updateable, and/or the like. Such storage devicesmay be configured to implement any appropriate data stores, includingwithout limitation, various file systems, database structures, and/orthe like.

The memory 1060 of the UE 1000 also can comprise software elements (notshown in FIG. 10), including an operating system, device drivers,executable libraries, and/or other code, such as one or more applicationprograms, which may comprise computer programs provided by variousembodiments, and/or may be designed to implement methods, and/orconfigure systems, provided by other embodiments, as described herein.Merely by way of example, one or more procedures described with respectto the method(s) discussed above may be implemented as code and/orinstructions in memory 1060 that are executable by the UE 1000 (and/orprocessing unit(s) 1010 or DSP 1020 within UE 1000). In an aspect, thensuch code and/or instructions can be used to configure and/or adapt ageneral-purpose computer (or other device) to perform one or moreoperations in accordance with the described methods.

FIG. 11 illustrates an embodiment of a TRP 1100, which can be utilizedas described herein above (e.g., in association with FIGS. 1-10) and maycorrespond with base station 120, gNB 210, a ng-eNB 214, TRP 310, TRP410, and/or TRP 510. The TRP 1100 may be configured to perform one ormore of the operations illustrated in the method 900 of FIG. 9 It shouldbe noted that FIG. 11 is meant only to provide a generalizedillustration of various components, any or all of which may be utilizedas appropriate.

The TRP 1100 is shown comprising hardware elements that can beelectrically coupled via a bus 1105 (or may otherwise be incommunication, as appropriate). The hardware elements may include aprocessing unit(s) 1110 which can include without limitation one or moregeneral-purpose processors, one or more special-purpose processors (suchas DSP chips, graphics acceleration processors, ASICs, and/or the like),and/or other processing structure or means. As shown in FIG. 11, someembodiments may have a separate DSP 1120, depending on desiredfunctionality. Location determination and/or other determinations basedon wireless communication may be provided in the processing unit(s) 1110and/or wireless communication interface 1130 (discussed below),according to some embodiments. The TRP 1100 also can include one or moreinput devices, which can include without limitation a keyboard, display,mouse, microphone, button(s), dial(s), switch(es), and/or the like; andone or more output devices, which can include without limitation adisplay, light emitting diode (LED), speakers, and/or the like.

The TRP 1100 might also include a wireless communication interface 1130,which may comprise without limitation a modem, a network card, aninfrared communication device, a wireless communication device, and/or achipset (such as a Bluetooth® device, an IEEE 802.11 device, an IEEE802.15.4 device, a Wi-Fi device, a WiMAX device, cellular communicationfacilities, etc.), and/or the like, which may enable the TRP 1100 tocommunicate as described herein. The wireless communication interface1130 may permit data and signaling to be communicated (e.g., transmittedand received) to UEs, other base stations/TRPs (e.g., eNB s, gNB s, andng-eNBs), and/or other network components, computer systems, and/or anyother electronic devices described herein. The communication can becarried out via one or more wireless communication antenna(s) 1132 thatsend and/or receive wireless signals 1134.

The TRP 1100 may also include a network interface 1180, which caninclude support of wireline communication technologies. The networkinterface 1180 may include a modem, network card, chipset, and/or thelike. The network interface 1180 may include one or more input and/oroutput communication interfaces to permit data to be exchanged with anetwork, communication network servers, computer systems, and/or anyother electronic devices described herein.

In many embodiments, the TRP 1100 may further comprise a memory 1160.The memory 1160 can include, without limitation, local and/or networkaccessible storage, a disk drive, a drive array, an optical storagedevice, a solid-state storage device, such as a RAM, and/or a ROM, whichcan be programmable, flash-updateable, and/or the like. Such storagedevices may be configured to implement any appropriate data stores,including without limitation, various file systems, database structures,and/or the like.

The memory 1160 of the TRP 1100 also may comprise software elements (notshown in FIG. 11), including an operating system, device drivers,executable libraries, and/or other code, such as one or more applicationprograms, which may comprise computer programs provided by variousembodiments, and/or may be designed to implement methods, and/orconfigure systems, provided by other embodiments, as described herein.Merely by way of example, one or more procedures described with respectto the method(s) discussed above may be implemented as code and/orinstructions in memory 1160 that are executable by the TRP 1100 (and/orprocessing unit(s) 1110 or DSP 1120 within TRP 1100). In an aspect, thensuch code and/or instructions can be used to configure and/or adapt ageneral-purpose computer (or other device) to perform one or moreoperations in accordance with the described methods.

FIG. 12 is a block diagram of an embodiment of a computer system 1200,which may be used, in whole or in part, to provide the functions of aserver or other network node described herein with regard to FIGS. 1-11and may correspond with location server 160, external client 180, LMF220, and/or other network-connected devices described herein. It shouldbe noted that FIG. 12 is meant only to provide a generalizedillustration of various components, any or all of which may be utilizedas appropriate. FIG. 12, therefore, broadly illustrates how individualsystem elements may be implemented in a relatively separated orrelatively more integrated manner. In addition, it can be noted thatcomponents illustrated by FIG. 12 can be localized to a single deviceand/or distributed among various networked devices, which may bedisposed at different geographical locations.

The computer system 1200 is shown comprising hardware elements that canbe electrically coupled via a bus 1205 (or may otherwise be incommunication, as appropriate). The hardware elements may includeprocessing unit(s) 1210, which may comprise without limitation one ormore general-purpose processors, one or more special-purpose processors(such as digital signal processing chips, graphics accelerationprocessors, and/or the like), and/or other processing structure, whichcan be configured to perform one or more of the methods describedherein. The computer system 1200 also may comprise one or more inputdevices 1215, which may comprise without limitation a mouse, a keyboard,a camera, a microphone, and/or the like; and one or more output devices1220, which may comprise without limitation a display device, a printer,and/or the like.

The computer system 1200 may further include (and/or be in communicationwith) one or more non-transitory storage devices 1225, which cancomprise, without limitation, local and/or network accessible storage,and/or may comprise, without limitation, a disk drive, a drive array, anoptical storage device, a solid-state storage device, such as a RAMand/or ROM, which can be programmable, flash-updateable, and/or thelike. Such storage devices may be configured to implement anyappropriate data stores, including without limitation, various filesystems, database structures, and/or the like. Such data stores mayinclude database(s) and/or other data structures used store andadminister messages and/or other information to be sent to one or moredevices via hubs, as described herein.

The computer system 1200 may also include a communications subsystem1230, which may comprise wireless communication technologies managed andcontrolled by a wireless communication interface 1233, as well as wiredtechnologies (such as Ethernet, coaxial communications, universal serialbus (USB), and the like). The wireless communication interface 1233 maysend and receive wireless signals 1255 (e.g., signals according to 5G NRor LTE) via wireless antenna(s) 1250. Thus the communications subsystem1230 may comprise a modem, a network card (wireless or wired), aninfrared communication device, a wireless communication device, and/or achipset, and/or the like, which may enable the computer system 1200 tocommunicate on any or all of the communication networks described hereinto any device on the respective network, including a User Equipment(UE), base stations and/or other TRPs, and/or any other electronicdevices described herein. Hence, the communications subsystem 1230 maybe used to receive and send data as described in the embodiments herein.

In many embodiments, the computer system 1200 will further comprise aworking memory 1235, which may comprise a RAM or ROM device, asdescribed above. Software elements, shown as being located within theworking memory 1235, may comprise an operating system 1240, devicedrivers, executable libraries, and/or other code, such as one or moreapplications 1245, which may comprise computer programs provided byvarious embodiments, and/or may be designed to implement methods, and/orconfigure systems, provided by other embodiments, as described herein.Merely by way of example, one or more procedures described with respectto the method(s) discussed above might be implemented as code and/orinstructions executable by a computer (and/or a processing unit within acomputer); in an aspect, then, such code and/or instructions can be usedto configure and/or adapt a general purpose computer (or other device)to perform one or more operations in accordance with the describedmethods.

A set of these instructions and/or code might be stored on anon-transitory computer-readable storage medium, such as the storagedevice(s) 1225 described above. In some cases, the storage medium mightbe incorporated within a computer system, such as computer system 1200.In other embodiments, the storage medium might be separate from acomputer system (e.g., a removable medium, such as an optical disc),and/or provided in an installation package, such that the storage mediumcan be used to program, configure, and/or adapt a general purposecomputer with the instructions/code stored thereon. These instructionsmight take the form of executable code, which is executable by thecomputer system 1200 and/or might take the form of source and/orinstallable code, which, upon compilation and/or installation on thecomputer system 1200 (e.g., using any of a variety of generallyavailable compilers, installation programs, compression/decompressionutilities, etc.), then takes the form of executable code.

It will be apparent to those skilled in the art that substantialvariations may be made in accordance with specific requirements. Forexample, customized hardware might also be used and/or particularelements might be implemented in hardware, software (including portablesoftware, such as applets, etc.), or both. Further, connection to othercomputing devices such as network input/output devices may be employed.

With reference to the appended figures, components that can includememory can include non-transitory machine-readable media. The term“machine-readable medium” and “computer-readable medium” as used herein,refer to any storage medium that participates in providing data thatcauses a machine to operate in a specific fashion. In embodimentsprovided hereinabove, various machine-readable media might be involvedin providing instructions/code to processing units and/or otherdevice(s) for execution. Additionally or alternatively, themachine-readable media might be used to store and/or carry suchinstructions/code. In many implementations, a computer-readable mediumis a physical and/or tangible storage medium. Such a medium may takemany forms, including but not limited to, non-volatile media andvolatile media. Common forms of computer-readable media include, forexample, magnetic and/or optical media, any other physical medium withpatterns of holes, a RAM, a programmable ROM (PROM), erasable PROM(EPROM), a FLASH-EPROM, any other memory chip or cartridge, or any othermedium from which a computer can read instructions and/or code.

The methods, systems, and devices discussed herein are examples. Variousembodiments may omit, substitute, or add various procedures orcomponents as appropriate. For instance, features described with respectto certain embodiments may be combined in various other embodiments.Different aspects and elements of the embodiments may be combined in asimilar manner. The various components of the figures provided hereincan be embodied in hardware and/or software. Also, technology evolvesand, thus many of the elements are examples that do not limit the scopeof the disclosure to those specific examples.

It has proven convenient at times, principally for reasons of commonusage, to refer to such signals as bits, information, values, elements,symbols, characters, variables, terms, numbers, numerals, or the like.It should be understood, however, that all of these or similar terms areto be associated with appropriate physical quantities and are merelyconvenient labels. Unless specifically stated otherwise, as is apparentfrom the discussion above, it is appreciated that throughout thisSpecification discussion utilizing terms such as “processing,”“computing,” “calculating,” “determining,” “ascertaining,”“identifying,” “associating,” “measuring,” “performing,” or the likerefer to actions or processes of a specific apparatus, such as a specialpurpose computer or a similar special purpose electronic computingdevice. In the context of this Specification, therefore, a specialpurpose computer or a similar special purpose electronic computingdevice is capable of manipulating or transforming signals, typicallyrepresented as physical electronic, electrical, or magnetic quantitieswithin memories, registers, or other information storage devices,transmission devices, or display devices of the special purpose computeror similar special purpose electronic computing device.

Terms, “and” and “or” as used herein, may include a variety of meaningsthat also is expected to depend, at least in part, upon the context inwhich such terms are used. Typically, “or” if used to associate a list,such as A, B, or C, is intended to mean A, B, and C, here used in theinclusive sense, as well as A, B, or C, here used in the exclusivesense. In addition, the term “one or more” as used herein may be used todescribe any feature, structure, or characteristic in the singular ormay be used to describe some combination of features, structures, orcharacteristics. However, it should be noted that this is merely anillustrative example and claimed subject matter is not limited to thisexample. Furthermore, the term “at least one of” if used to associate alist, such as A, B, or C, can be interpreted to mean any combination ofA, B, and/or C, such as A, AB, AA, AAB, AABBCCC, etc.

Having described several embodiments, various modifications, alternativeconstructions, and equivalents may be used without departing from thescope of the disclosure. For example, the above elements may merely be acomponent of a larger system, wherein other rules may take precedenceover or otherwise modify the application of the various embodiments.Also, a number of steps may be undertaken before, during, or after theabove elements are considered. Accordingly, the above description doesnot limit the scope of the disclosure.

In view of this description embodiments may include differentcombinations of features. Implementation examples are described in thefollowing numbered clauses:

-   Clause 1. A method of Timing Advance (TA) handling for sidelink    (SL)-assisted positioning of a first User Equipment (UE), the method    comprising: determining the first UE is configured to transmit an SL    Positioning Reference Signal (SL-PRS) to a second UE to perform the    SL-assisted positioning; determining a length of time for a guard    period based on a configuration of the first UE for transmitting the    SL-PRS, wherein the guard period comprises a period of time during    which the SL-PRS is transmitted by the first UE; and sending, to a    serving Transmission Reception Point (TRP) of the first UE, a    message indicating the guard period and comprising a TA-related    request, wherein the TA-related request includes: a request to    postpone applying a TA command received by the first UE until after    the guard period, or a request for the serving TRP not to send a TA    command to the first UE during the guard period.-   Clause 2. The method of clause 1, wherein: the TA-related request    comprises the request to postpone applying the TA command received    by the first UE until after the guard period; and the message is    sent by the first UE during a SL-PRS positioning session during    which the SL-PRS is transmitted by the first UE to the second UE.-   Clause 3. The method of clause 1 or 2, wherein determining the    length of time for the guard period comprises selecting the length    of time from a predetermined list of enumerated values.-   Clause 4. The method of any of clauses 1-3, wherein determining the    length of time for the guard period is further based on a remaining    amount of time remaining in the SL-PRS positioning session.-   Clause 5. The method of any of clauses 1-4, wherein sending the    message comprises including the message in: UCI (Uplink Control    Information), a Radio Resource Control (RRC) message, or a Medium    Access Control (MAC) Control Element (CE), or any combination    thereof.-   Clause 6. The method of any of clauses 1-5, further comprising:    receiving, at the first UE, an indication from the serving TRP of an    acceptance of the TA-related request; and postponing the applying of    the TA command received by the first UE until after the guard    period.-   Clause 7. The method of clause 1, wherein: the TA-related request    comprises the request for the serving TRP not to send the TA command    to the first UE during the guard period; and message is sent by a    location server or the first UE prior to an SL-PRS positioning    session during which the SL-PRS is transmitted by the first UE to    the second UE.-   Clause 8. The method of any of clauses 1-7, further comprising:    receiving, at the first UE, a response to the message from the    serving TRP, wherein the response is indicative of a rejection of    the TA-related request; receiving, at the first UE, a TA command    from the serving TRP during the guard period; and applying the TA    command during the guard period.-   Clause 9. The method of clause 8, further comprising sending, from    the first UE, a report to a network node, wherein the report    comprises: a time adjustment of a transmission time of the SL-PRS    based on applying the TA command during the guard period, a PRS    resource identifier (ID) of the SL-PRS, and an indication of one or    more SL-PRS occasions impacted by applying the TA command.-   Clause 10. The method of clause 9, wherein the network node    comprises a location server or the second UE.-   Clause 11. A method of Timing Advance (TA) handling for sidelink    (SL)-assisted positioning of a first User Equipment (UE), the method    comprising: receiving, at a serving Transmission Reception Point    (TRP) of the first UE, a message from a network node, the message    indicating a guard period and comprising a TA-related request,    wherein: the guard period comprises a period of time during which an    SL Positioning Reference Signal (SL-PRS) is transmitted by the first    UE to a second UE; and the TA-related request comprises: a request    to postpone applying a TA command received by the first UE until    after the guard period, or a request for the serving TRP not to send    a TA command to the first UE during the guard period; determining a    response to the message based on an applicable TA priority    condition; and sending the response to the network node.-   Clause 12. The method of clause 11, wherein the network node    comprises the first UE or a location server.-   Clause 13. The method of clause 11 or 12, wherein the response is    either: indicative of a rejection of TA-related request, or    indicative of an acceptance of TA-related request TA-related    request.-   Clause 14. The method of any of clauses 11-13, wherein the    applicable TA priority condition comprises the first UE being    engaged in a handover procedure.-   Clause 15. A device for providing Timing Advance (TA) handling for    sidelink (SL)-assisted positioning of a first User Equipment (UE),    the device comprising: a communication interface; a memory; and one    or more processing units communicatively coupled with the    communication interface and the memory, the one or more processing    units configured to: determine the first UE is configured to    transmit an SL Positioning Reference Signal (SL-PRS) to a second UE    to perform the SL-assisted positioning; determine a length of time    for a guard period based on a configuration of the first UE for    transmitting the SL-PRS, wherein the guard period comprises a period    of time during which the SL-PRS is transmitted by the first UE; and    send, to a serving Transmission Reception Point (TRP) of the first    UE via the communication interface, a message indicating the guard    period and comprising a TA-related request, wherein the TA-related    request includes: a request to postpone applying a TA command    received by the first UE until after the guard period, or a request    for the serving TRP not to send a TA command to the first UE during    the guard period.-   Clause 16. The device of clause 15, wherein the device comprises the    first UE, and wherein: the TA-related request comprises the request    to postpone applying the TA command received by the first UE until    after the guard period; and the one or more processing units are    configured to send the message during a SL-PRS positioning session    during which the SL-PRS is transmitted by the first UE to the second    UE.-   Clause 17. The device of clause 15 or 16, wherein, to determine the    length of time for the guard period, the one or more processing    units are configured select the length of time from a predetermined    list of enumerated values.-   Clause 18. The device of any of clauses 15-17, wherein the one or    more processing units are configured to further base determining the    length of time for the guard period on a remaining amount of time    remaining in the SL-PRS positioning session.-   Clause 19. The device of any of clauses 15-18, wherein the one or    more processing units are configured to send the message in: UCI    (Uplink Control Information), a Radio Resource Control (RRC)    message, or a Medium Access Control (MAC) Control Element (CE), or    any combination thereof.-   Clause 20. The device of any of clauses 15-19, wherein the one or    more processing units are further configured to: receive an    indication from the serving TRP of an acceptance of the TA-related    request; and postpone the applying of the TA command received by the    first UE until after the guard period.-   Clause 21. The device of clause 15, wherein the device comprises a    location server or the first UE, and wherein: the TA-related request    comprises the request for the serving TRP not to send the TA command    to the first UE during the guard period; and the one or more    processing units are configured to send the message prior to an    SL-PRS positioning session during which the SL-PRS is transmitted by    the first UE to the second UE.-   Clause 22. The device of any of clauses 15-21, wherein the device    comprises the first UE, and wherein the one or more processing units    are further configured to: receive, via the communication interface,    a response to the message from the serving TRP, wherein the response    is indicative of a rejection of the TA-related request; receive, via    the communication interface, a TA command from the serving TRP    during the guard period; and apply the TA command during the guard    period.-   Clause 23. The device of clause 22, wherein the device comprises the    first UE, and wherein the one or more processing units are further    configured to send a report to a network node, the report    comprising: a time adjustment of a transmission time of the SL-PRS    based on applying the TA command during the guard period, a PRS    resource identifier (ID) of the SL-PRS, and an indication of one or    more SL-PRS occasions impacted by applying the TA command.-   Clause 24. The device of clause 23, wherein the network node    comprises a location server or the second UE.-   Clause 25. A device for providing Timing Advance (TA) handling for    sidelink (SL)-assisted positioning of a first User Equipment (UE),    the device comprising: a communication interface; a memory; and one    or more processing units communicatively coupled with the    communication interface and the memory, the one or more processing    units configured to: receive, via the communication interface, a    message from a network node, the message indicating a guard period    and comprising a TA-related request, wherein: the guard period    comprises a period of time during which an SL Positioning Reference    Signal (SL-PRS) is transmitted by the first UE to a second UE; and    the TA-related request comprises: a request to postpone applying a    TA command received by the first UE until after the guard period, or    a request for a serving Transmission Reception Point (TRP) not to    send a TA command to the first UE during the guard period; determine    a response to the message based on an applicable TA priority    condition; and send, via the communication interface, the response    to the network node.-   Clause 26. The device of clause 25, wherein the network node    comprises the first UE or a location server.-   Clause 27. The device of clause 25 or 26, wherein the response is    either: indicative of a rejection of TA-related request, or    indicative of an acceptance of TA-related request TA-related    request.-   Clause 28. The device of any of clauses 25-27, wherein the    applicable TA priority condition comprises the first UE being    engaged in a handover procedure.-   Clause 29. A device comprising: means for determining a first User    Equipment (UE) is configured to transmit an sidelink (SL)    Positioning Reference Signal (SL-PRS) to a second UE to perform    SL-assisted positioning of the first UE; means for determining a    length of time for a guard period based on a configuration of the    first UE for transmitting the SL-PRS, wherein the guard period    comprises a period of time during which the SL-PRS is transmitted by    the first UE; and means for sending, to a serving Transmission    Reception Point (TRP) of the first UE, a message indicating the    guard period and comprising a Timing Advance (TA)-related request,    wherein the TA-related request includes: a request to postpone    applying a TA command received by the first UE until after the guard    period, or a request for the serving TRP not to send a TA command to    the first UE during the guard period.-   Clause 30. The device of clause 29, wherein: the TA-related request    comprises the request to postpone applying the TA command received    by the first UE until after the guard period; and the message is    sent by the first UE during a SL-PRS positioning session during    which the SL-PRS is transmitted by the first UE to the second UE.-   Clause 31. The device of clause 29 or 30, wherein the means for    determining the length of time for the guard period comprise means    for selecting the length of time from a predetermined list of    enumerated values.-   Clause 32. The device of any of clauses 29-31, wherein the means for    determining the length of time for the guard period further base the    length of time for the guard period on a remaining amount of time    remaining in the SL-PRS positioning session.-   Clause 33. The device of any of clauses 29-32, wherein the means for    sending the message comprise means for including the message in: UCI    (Uplink Control Information), a Radio Resource Control (RRC)    message, or a Medium Access Control (MAC) Control Element (CE), or    any combination thereof.-   Clause 34. The device of any of clauses 29-33, further comprising:    means for receiving an indication from the serving TRP of an    acceptance of the TA-related request; and means for postponing the    applying of the TA command at the first UE until after the guard    period.-   Clause 35. The device of clause 29, wherein: the TA-related request    comprises the request for the serving TRP not to send the TA command    to the first UE during the guard period; and message is sent by a    location server or the first UE prior to an SL-PRS positioning    session during which the SL-PRS is transmitted by the first UE to    the second UE.-   Clause 36. The device of any of clauses 29-35, further comprising:    means for receiving a response to the message from the serving TRP,    wherein the response is indicative of a rejection of the TA-related    request; means for receiving a TA command from the serving TRP    during the guard period; and means for applying the TA command at    the first UE during the guard period.-   Clause 37. The device of clause 36, further comprising means for    sending, from the first UE, a report to a network node, wherein the    report comprises: a time adjustment of a transmission time of the    SL-PRS based on applying the TA command during the guard period, a    PRS resource identifier (ID) of the SL-PRS, and an indication of one    or more SL-PRS occasions impacted by applying the TA command.-   Clause 38. The device of clause 37, wherein the network node    comprises a location server or the second UE.-   Clause 39. A device comprising: means for receiving a message from a    network node, the message indicating a guard period and comprising a    Timing Advance (TA)-related request, wherein: the guard period    comprises a period of time during which an sidelink (SL) Positioning    Reference Signal (SL-PRS) is transmitted by a first User Equipment    (UE) to a second UE; and the TA-related request comprises: a request    to postpone applying a TA command received by the first UE until    after the guard period, or a request for a serving Transmission    Reception Point (TRP) not to send a TA command to the first UE    during the guard period; means for determining a response to the    message based on an applicable TA priority condition; and means for    sending the response to the network node.-   Clause 40. The device of clause 39, wherein the network node    comprises the first UE or a location server.-   Clause 41. The device of clause 39 or 40, wherein the response is    either: indicative of a rejection of TA-related request, or    indicative of an acceptance of TA-related request TA-related    request.-   Clause 42. The device of any of clauses 39-41, wherein the    applicable TA priority condition comprises the first UE being    engaged in a handover procedure.-   Clause 43. A non-transitory computer-readable medium storing    instructions for Timing Advance (TA) handling for sidelink    (SL)-assisted positioning of a first User Equipment (UE), the    instructions comprising code for: determining the first UE is    configured to transmit an SL Positioning Reference Signal (SL-PRS)    to a second UE to perform the SL-assisted positioning; determining a    length of time for a guard period based on a configuration of the    first UE for transmitting the SL-PRS, wherein the guard period    comprises a period of time during which the SL-PRS is transmitted by    the first UE; and sending, to a serving Transmission Reception Point    (TRP) of the first UE, a message indicating the guard period and    comprising a TA-related request, wherein the TA-related request    includes: a request to postpone applying a TA command received by    the first UE until after the guard period, or a request for the    serving TRP not to send a TA command to the first UE during the    guard period.-   Clause 44. The non-transitory computer-readable medium of clause 43,    wherein: the TA-related request comprises the request to postpone    applying the TA command received by the first UE until after the    guard period; and the message is sent by the first UE during a    SL-PRS positioning session during which the SL-PRS is transmitted by    the first UE to the second UE.-   Clause 45. The non-transitory computer-readable medium of clause 43    or 44, wherein the code for determining the length of time for the    guard period comprises code for selecting the length of time from a    predetermined list of enumerated values.-   Clause 46. The non-transitory computer-readable medium of any of    clauses 43-45, wherein the code for determining the length of time    for the guard period further bases the length of time for the guard    period on a remaining amount of time remaining in the SL-PRS    positioning session.-   Clause 47. The non-transitory computer-readable medium of any of    clauses 43-46, wherein the code for sending the message comprises    code for including the message in: UCI (Uplink Control Information),    a Radio Resource Control (RRC) message, or a Medium Access Control    (MAC) Control Element (CE), or any combination thereof.-   Clause 48. The non-transitory computer-readable medium of any of    clauses 43-47, wherein the instructions further comprise code for:    receiving, at the first UE, an indication from the serving TRP of an    acceptance of the TA-related request; and postponing the applying of    the TA command received by the first UE until after the guard    period.-   Clause 49. The non-transitory computer-readable medium of clause 43,    wherein: the TA-related request comprises the request for the    serving TRP not to send the TA command to the first UE during the    guard period; and message is sent by a location server or the first    UE prior to an SL-PRS positioning session during which the SL-PRS is    transmitted by the first UE to the second UE.-   Clause 50. The non-transitory computer-readable medium of any of    clauses 43-49, wherein the instructions further comprise code for:    receiving, at the first UE, a response to the message from the    serving TRP, wherein the response is indicative of a rejection of    the TA-related request; receiving, at the first UE, a TA command    from the serving TRP during the guard period; and applying the TA    command during the guard period.-   Clause 51. The non-transitory computer-readable medium of clause 50,    wherein the instructions further comprise code for sending, from the    first UE, a report to a network node, wherein the report comprises:    a time adjustment of a transmission time of the SL-PRS based on    applying the TA command during the guard period, a PRS resource    identifier (ID) of the SL-PRS, and an indication of one or more    SL-PRS occasions impacted by applying the TA command.-   Clause 52. The non-transitory computer-readable medium of clause 51,    wherein the network node comprises a location server or the second    UE.-   Clause 53. A non-transitory computer-readable medium storing    instructions for Timing Advance (TA) handling for sidelink    (SL)-assisted positioning of a first User Equipment (UE), the    instructions comprising code for: receiving, at a serving    Transmission Reception Point (TRP) of the first UE, a message from a    network node, the message indicating a guard period and comprising a    TA-related request, wherein: the guard period comprises a period of    time during which an SL Positioning Reference Signal (SL-PRS) is    transmitted by the first UE to a second UE; and the TA-related    request comprises: a request to postpone applying a TA command    received by the first UE until after the guard period, or a request    for the serving TRP not to send a TA command to the first UE during    the guard period; determining a response to the message based on an    applicable TA priority condition; and sending the response to the    network node.-   Clause 54. The non-transitory computer-readable medium of clause 53,    wherein the network node comprises the first UE or a location    server.-   Clause 55. The non-transitory computer-readable medium of clause 53    or 54, wherein the response is either: indicative of a rejection of    TA-related request, or indicative of an acceptance of TA-related    request TA-related request.-   Clause 56. The non-transitory computer-readable medium of any of    clauses 53-55, wherein the applicable TA priority condition    comprises the first UE being engaged in a handover procedure.

What is claimed is:
 1. A method of Timing Advance (TA) handling forsidelink (SL)-assisted positioning of a first User Equipment (UE), themethod comprising: receiving, at a first UE, a TA command from a servingTRP during a guard period, wherein the guard period comprises a periodof time during which an SL Positioning Reference Signal (SL-PRS) istransmitted by the first UE; applying the TA command during the guardperiod; transmitting the SL-PRS to a second UE; and sending, from thefirst UE, a report to a network node, wherein the report comprises: atime adjustment of a transmission time of the SL-PRS based on applyingthe TA command during the guard period, a PRS resource identifier (ID)of the SL-PRS, and an indication of one or more occasions of the SL-PRSimpacted by applying the TA command.
 2. The method of claim 1, furthercomprising, prior to receiving the TA command, determining a length oftime for a guard period based on a configuration of the first UE fortransmitting the SL-PRS.
 3. The method of claim 2, further comprising:sending, to a serving Transmission Reception Point (TRP) of the firstUE, a message indicating the guard period and comprising a TA-relatedrequest, wherein the TA-related request includes: a request to postponeapplying a TA command received by the first UE until after the guardperiod, or a request for the serving TRP not to send a TA command to thefirst UE during the guard period; and receiving, at the first UE, aresponse to the message from the serving TRP, wherein the response isindicative of a rejection of the TA-related request; wherein thetransmitting the SL-PRS is responsive, at least in part, to therejection of the TA-related request.
 4. The method of claim 3, wherein:the TA-related request comprises the request to postpone applying the TAcommand received by the first UE until after the guard period; and themessage is sent by the first UE during a SL-PRS positioning sessionduring which the SL-PRS is transmitted by the first UE.
 5. The method ofclaim 4, wherein sending the message comprises including the message in:UCI (Uplink Control Information), a Radio Resource Control (RRC)message, or a Medium Access Control (MAC) Control Element (CE), or anycombination thereof.
 6. The method of claim 3, wherein: the TA-relatedrequest comprises the request for the serving TRP not to send the TAcommand to the first UE during the guard period; and the message is sentby the first UE prior to an SL-PRS positioning session during which theSL-PRS is transmitted by the first UE to the second UE.
 7. The method ofclaim 2, wherein determining the length of time for the guard periodcomprises selecting the length of time from a predetermined list ofenumerated values.
 8. The method of claim 2, wherein determining thelength of time for the guard period is further based on a remainingamount of time remaining in an SL-PRS positioning session.
 9. The methodof claim 1, wherein the network node comprises a location server or thesecond UE.
 10. A first User Equipment (UE) comprising: a transceiver; amemory; and one or more processors communicatively coupled with thetransceiver and the memory, wherein the one or more processors areconfigured to: receive, via the transceiver, a Timing Advance (TA)command from a serving TRP of the first UE during a guard period,wherein the guard period comprises a period of time during which an SLPositioning Reference Signal (SL-PRS) is transmitted by the first UE;apply the TA command during the guard period; transmit the SL-PRS viathe transceiver to a second UE; and send, via the transceiver, a reportto a network node, wherein the report comprises: a time adjustment of atransmission time of the SL-PRS based on applying the TA command duringthe guard period, a PRS resource identifier (ID) of the SL-PRS, and anindication of one or more occasions of the SL-PRS impacted by applyingthe TA command.
 11. The first UE of claim 10, wherein the one or moreprocessors are further configured to, prior to receiving the TA command,determine a length of time for a guard period based on a configurationof the first UE for transmitting the SL-PRS.
 12. The first UE of claim11, wherein the one or more processors are further configured to: send,to a serving Transmission Reception Point (TRP) of the first UE, amessage indicating the guard period and comprising a TA-related request,wherein the TA-related request includes: a request to postpone applyinga TA command received by the first UE until after the guard period, or arequest for the serving TRP not to send a TA command to the first UEduring the guard period; and receive, at the first UE, a response to themessage from the serving TRP, wherein the response is indicative of arejection of the TA-related request; wherein the transmitting the SL-PRSis responsive, at least in part, to the rejection of the TA-relatedrequest.
 13. The first UE of claim 12, wherein the one or moreprocessors are further configured to send the message during a SL-PRSpositioning session during which the SL-PRS is transmitted by the firstUE.
 14. The first UE of claim 12, wherein, to send the message, the oneor more processors are configured to include the message in: UCI (UplinkControl Information), a Radio Resource Control (RRC) message, or aMedium Access Control (MAC) Control Element (CE), or any combinationthereof.
 15. The first UE of claim 12, wherein the one or moreprocessors are further configured to send the message prior to an SL-PRSpositioning session during which the SL-PRS is transmitted by the firstUE to the second UE.
 16. The first UE of claim 11, wherein, to determinethe length of time for the guard period, the one or more processors areconfigured to select the length of time from a predetermined list ofenumerated values.
 17. The first UE of claim 11, the one or moreprocessors are configured to determine the length of time for the guardperiod further based on a remaining amount of time remaining in anSL-PRS positioning session.
 18. The first UE of claim 10, wherein thenetwork node comprises a location server or the second UE.
 19. Anapparatus for Timing Advance (TA) handling for sidelink (SL)-assistedpositioning of a first User Equipment (UE), the apparatus comprising:means for receiving a TA command from a serving TRP during a guardperiod, wherein the guard period comprises a period of time during whichan SL Positioning Reference Signal (SL-PRS) is transmitted by the firstUE; means for applying the TA command during the guard period; means fortransmitting the SL-PRS to a second UE; and means for sending a reportto a network node, wherein the report comprises: a time adjustment of atransmission time of the SL-PRS based on applying the TA command duringthe guard period, a PRS resource identifier (ID) of the SL-PRS, and anindication of one or more occasions of the SL-PRS impacted by applyingthe TA command.
 20. The apparatus of claim 19, further comprising meansfor determining, prior to receiving the TA command, a length of time fora guard period based on a configuration of the first UE for transmittingthe SL-PRS.
 21. The apparatus of claim 20, further comprising: means forsending, to a serving Transmission Reception Point (TRP) of the firstUE, a message indicating the guard period and comprising a TA-relatedrequest, wherein the TA-related request includes: a request to postponeapplying a TA command received by the first UE until after the guardperiod, or a request for the serving TRP not to send a TA command to thefirst UE during the guard period; and means for receiving, at the firstUE, a response to the message from the serving TRP, wherein the responseis indicative of a rejection of the TA-related request; wherein thetransmitting the SL-PRS is responsive, at least in part, to therejection of the TA-related request.
 22. The apparatus of claim 21,wherein the means for sending the message comprises means for includingthe message in: UCI (Uplink Control Information), a Radio ResourceControl (RRC) message, or a Medium Access Control (MAC) Control Element(CE), or any combination thereof.
 23. The apparatus of claim 20, whereinthe means for determining the length of time for the guard periodcomprises means for selecting the length of time from a predeterminedlist of enumerated values.
 24. The apparatus of claim 20, whereindetermining the length of time for the guard period is further based ona remaining amount of time remaining in an SL-PRS positioning session.25. The apparatus of claim 19, wherein the network node comprises alocation server or the second UE.
 26. A non-transitory computer-readablemedium storing instructions for Timing Advance (TA) handling forsidelink (SL)-assisted positioning of a first User Equipment (UE), theinstructions comprising code for: receiving, at a first UE, a TA commandfrom a serving TRP during a guard period, wherein the guard periodcomprises a period of time during which an SL Positioning ReferenceSignal (SL-PRS) is transmitted by the first UE; applying the TA commandduring the guard period; transmitting the SL-PRS to a second UE; andsending, from the first UE, a report to a network node, wherein thereport comprises: a time adjustment of a transmission time of the SL-PRSbased on applying the TA command during the guard period, a PRS resourceidentifier (ID) of the SL-PRS, and an indication of one or moreoccasions of the SL-PRS impacted by applying the TA command.
 27. Thecomputer-readable medium of claim 26, wherein the instructions furthercomprise code for, prior to receiving the TA command, determining alength of time for a guard period based on a configuration of the firstUE for transmitting the SL-PRS.
 28. The computer-readable medium ofclaim 27, wherein the instructions further comprise code for: sending,to a serving Transmission Reception Point (TRP) of the first UE, amessage indicating the guard period and comprising a TA-related request,wherein the TA-related request includes: a request to postpone applyinga TA command received by the first UE until after the guard period, or arequest for the serving TRP not to send a TA command to the first UEduring the guard period; and receiving, at the first UE, a response tothe message from the serving TRP, wherein the response is indicative ofa rejection of the TA-related request; wherein the transmitting theSL-PRS is responsive, at least in part, to the rejection of theTA-related request.
 29. The computer-readable medium of claim 28,wherein the code for sending the message comprises code for includingthe message in: UCI (Uplink Control Information), a Radio ResourceControl (RRC) message, or a Medium Access Control (MAC) Control Element(CE), or any combination thereof.
 30. The computer-readable medium ofclaim 27, wherein the code for determining the length of time for theguard period comprises code for selecting the length of time from apredetermined list of enumerated values.